How to avoid people not accepting their gifts after contacting them for several times through steam

How many time did you wait? Because he could be playing MatchMaking and can't answer.

By having control over who wins your games
Send the game to his email, take it from there after 7 days have passed, or maybe show proof to support on how you tried getting in contact with the winner...but there is no way to actually avoid such people

Since all of your created giveaways are already marked as received, I assume that this is a past issue or something?
How long did you wait? Keep in mind that both parties have a week to make the exchange.

My suggestion is to send an email explaining you want a reply first before sending the gift to ensure the email address is used. If you go more than five days without a response to that, send a friend request on Steam as well to try and get their attention.

Users do have 7 days to accept the gift, so.....yeah.

I had one like this. Tried to contact him after a few days, no luck, so waited 7 and sent a ticket to request feedback. Then blacklisted him. Not much better you can do about it.
Maybe just wishful thinking, but since I started making private giveaways on forum, I've received more "thanks" and no such problems with winners. I think the main page has a greater percentage of weird people.

Some people idle CSGO for items. Other people idle for cards as well, so just because Steam says they're playing a game doesn't mean they are.

The winner has 7 full days from the end of the giveaway to activate and mark the gift.

karrie7...ever see the movie "hes just not that into you" csgo over rules chicks messages voice mail phones etc... anyday

You can send them an email, saying that you want a reply before sending the gift.
You may also put that info on the giveaway.
It's also good to add them on steam asap, and wait for contact, dont even bother trying to contact them more than that, they are the ones supposed to contact you since they won the game.

I have same situation here. He's online on this site more than 5x and I'm waiting for 2 days without any answer from him.

I have 2 people doing the same on my giveaways.

I've only had one person ever take a while to accept a gift (It was really annoying too cause I needed him to accept so I could move up a level).. actually I should be more specific, he used the code, but didn't mark received.
Everyone else normally accepts/marks received within a day.

the last giveaway I did, the winner hasn't marked it as received, and it says they're suspended for 2 weeks, so that's fun.... hopefully they will mark it received after that.

+4 level giveaways and you kinda reduce risks of any problems

I've dealt with similar people... in fact, I'm currently dealing with one. They seem to be online often and can't even be bothered to respond to a comment I've left on one of their giveaways. Ffs.

This happened to me too. The user didn't contact me for a giveaway. He just marked it as not received for the key I had sent him. I added him on Steam. Didn't accept my request. User hasn't given away any games so cannot comment on that either. :/

It gets really annoying when you are trying to do an even of giveaways and are counting on that spot to open up soon so you can get more giveaways going, esp if it is giveaways of multiple copies and you had everything scheduled out pre-event, all nice and neat in a spreadsheet. >_< And I saw your comment that you only do giveaways for folks your level and up... From reading around on the forums since being here... level doesn't always mean they're "good" people or easier to deal with. While I do not know who they are and wouldn't name names even if I did, I have heard there are a few of the much higher level folks that can get downright pain in the ass to deal with. So while level DOES get rid of a lot of the hassle, it won't get rid of all it, sadly.

Welcome to my world: chasing (mostly Russian) CS:GO players because they don't care about this site, don't understand it, or just enter everything without knowing what the game even is and not caring about it at all.

If you are lucky, they just didn't care and you can reroll after seven days so the game may end up at someone who entered because they wanted it, not because "it's cheap, therefore I am entitled to it, regardless of if I want it or not." (If anything, this mentality should be erased from Eastern Europe, like, right now.)

If you are less lucky, pestering them enough will make them mark it as received.

If you are unlucky, they just got the key and regifted it, posted it on GameMiner, trying to sell it at G2A…
In this case you may reroll, and if the winner complains about a duplicate key, you may try the support of the site you got it from: ask for a new key while revoking the previous one. If the original winner really sold/stole, it, he'll be in a shock when he gets a nice -rep for peddling in stolen keys.
Alternatively, if the winner has a history of not-activated keys, just ask for a forced positive feedback after you shown support that you revealed/sent the key.

idiots
playing csgo..

Sounds legit.

I had 2 GAs lately where the winner didnt show up on the first one on SG nor on Steam and didnt react to any contact, the second was on SG and Steam but didnt react to any contact neither.
In both cases i waited the 7 days and then requested a new winner from support after proofing my contact tries.
Both where 4+ GAs.
There are 2 people more on my really small blacklist (less than 10 total), guess who.

This is happening to me, still waiting an answer from the winner, he connect and disconnect on steam and NEVER answer when I talk to him.

I'm waiting for a winner to accept a gift from my inventory for 4+ months now. Can't do re-roll because there were less entries than gift copies. And they are active on Steam, but refused request and do not answer to e-mails. Not sure why they entered the giveaway in the first place.