I made a giveaway and its been 2 days and the person still has not received it.

He has 1 week time to act.

If you sent it with email, it may have ended up in spam.

I have a question that is sort of related to this. Do I have to wait a week to say I didn't received the gift because, the person who made the giveaway already emailed me that he used his key the day that the giveaway was over

And to answer your next question which will most likely pertain to contributor value, please read this helpful post by Bobofatt:

Games which have been in bundles or otherwise made widely available at little or no cost are added to the bundle list. Games in this list will not add more than 20% (1/5) of your non-bundle contributions, disregarding the first $25. For more detailed information, see this thread.

In order to receive any additional value from your current bundle gifts, partial or otherwise, you will need to contribute more in non-bundle games.

2 days?!? He must be dead.

Some people travel for 2 days. Do you really spend all of your time at the computer?

Wait until it's been a week. For one of mine, I had to wait the full length of time because the winner didn't check their email until the last day they had left.