Does how many entries your giveaway gets matter

5 so that it is counted, after that it is equal, you will get your CV.

As long as the giveaway gets at least 5 entries to get the contribution value, other than that, entries don't matter.

To prevent abuse - say creating a second account, letting that one win all kinds of expensive things you didn't actually give just to get your level up, and then have that account get banned while you reap the rewards - you need to have a minimum of 5 entries in private/group giveaways to actually get the CV value. Beyond that there's no difference.

It's wise to also note that there is no 5 entries requirement in public giveaways. Even 1 counts.

So technically I can create an hour giveaway and it wouldn't matter. I understand the concept of having 5 people, but anything past that is pointless?

1 entry for public, 5+ for invite/group/whitelist.
http://www.steamgifts.com/about/faq

What are levels, and how can I increase my level?
-2. If a giveaway is invite only, or for a whitelist or Steam group, it will only add value towards your level if it receives 5 or more entries.