Seems like he didnt claim it, so you could report him for not redeeming..

What about asking support?

Okay, what the fuck, guys? How is this a difficult question you can't answer yourself? This is not something Support needs to deal with. I figured you lot were smarter than that.

Stelio, I can't answer why the winner marked as recieved (might be they just wanted the green banner gone and forgot to update it after you apparently failed to give the gift), but if it's still in your inventory, they haven't claimed it at all. Contact the winner, let them know it's there. If they don't answer (or you want to just give it to someone who'll actually check their e-mail (or gave their actual, real e-mail address)), feel free to return the gift to your inventory (click Send Gift and then there's a new option) and then ask us for a reroll.

I've been in situations where sending a game through email to a known friend account outside of Sgifts has actually allowed me to retain the game and him recieving the game at the same time, now i don't really know why or how it occured to me, but it has happened twice already (once with a Terraria 4-pack, ending in a 5-pack), and Half Life 2, having sent it to two different people in the end and them still being able to activate.
Like i said, i have yet to know why, and even if i would i wouldn't be posting it publicly, but mentioning it to Steam support (actually i had already)

Perhaps you should first contact the person and ask personally if he really activated the game, and if possible, a proof; in the case he cannot provide a proof, THEN consider contact SG support. If he does have activated, and provide proof, then perhaps present a ticket in Steam support, could be a bug like it happened to me before.

I hate it when you guys fight ;_;

Thanks for all the help guys, I'm going to email the winner and see what is going on. If they say it's activated then get in touch with steam, if not then I'll sort something else out :)