Winner won't accept gift. What do?

Give it to me.

Call me the winner :P

Nah message the mods of this site about it I guess and reroll your giveaway

Give me that gift :D

If you still haven't been able to contact him after one week, use support to contact the mods.

Redo the giveaway , he missed hes chance

Contact the mods.

I say give him a week, then talk to the mods and redo the giveaway. His fault for being absentee.

It will be hard to redo the giveaway though since it's a steam key.

I guess try the mods now and if they take too long to get back to you, redo it somehow.
Or check your friends list for someone you feel deserves and wants it, I guess.

step 1: wait one week after the giveaway has ended
step 2: if no contact from winner-> contact support
step 3: work with the friendly support staff to create a solution to your particular problem