what do i do if i sent a gift and a person does not claim it?

You must wait one week, this is time for send and receive the game. If winner didn't claim You should reroll for new winner, but You must be sure that the key or link isn't used. Or You can contact with support

This is why you don't give games by blind email.

If the person has not accepted/activated the game, you may request a re-roll after seven days by contacting Support and showing the evidence for your attempt to "deliver."

That is all assuming you can "take away" your game/key/link/whatever, of course. If you gave him or her a key or link which you can't revoke, he or she could just activate the game, anyway, leaving you in the position of having to get another copy for the re-roll winner.

thats why i add my winners to steam, to look at them closely, even when they are sleeping, and make sure that they not only activate the game, but play it and enjoy it.....

wait a week, if the game still available re-roll a get another winner, if the game is claimed but he dosent mark it as recieved then contact support.