Yes, but no matter what you think, on steamgifts are rules, the winner have a 7 days period of time after he won the gift, to activate it. And the giveaway you mentioned the winner didn't confirmed only finished 1 day ago, so he have 6 more days to confirm he received the gift, before you can ask for a reroll for another winner. I just pointed this to you because if you want to ask steamgifts for another winner of the giveaway you must make a ticket for a re-roll, and you can only make that ticket after one week pass. :)
There, according to steamgifts FAQ: "If your gift has been activated or redeemed by the winner, and they have not left feedback after one week, please create a support ticket to request received feedback. A support member will review your ticket, and if the gift is activated on the winner's Steam account, they will update the feedback to "Received"."

it work in both direction, you have 7 days to send your game
sometimes, winner of my giveaways took 2-3 weeks to redeem that
i know it's boring for low level cause sometimes you just want to create a new giveaway and you must wait
but there are the rules and nobody will reroll your giveaway in the support if you don't respect them