Question about money from father for house purchase

So we are selling our house and buying a new one. Both houses are under contract with closing dates on the 21st and 22nd. We have been approved for the loan from our lender. Just found out yesterday our realtor forgot about our heloc when giving us numbers and just got the closing agreement from the lawyer and we are getting almost half of what our realtor originally told us. It was not enough to cover the down payment and we were also using the money to pay for our move and other things like storage and hotel (around 13k). We can’t be without a house as I’m starting a new job on the 4th, it’s in a different city, I have a 4yr old and wife is 7 months pregnant. My father wire transferred $50k to our joint bank account to be able to cover this in such a short time. My wife is getting 48k but not before closing hence I got it from my dad. My lender is ok with this and said they just need a gift letter from my father and I know he needs to file a 709 at the end of the year since it’s over the $19k. We want to pay him back once my wife receives her check in about 2-3 weeks. Can I gift him back the 50k and file a 709 myself in that short a time period from when he gave it to us? If I do will it count as income for him to get taxed on? How should I go about getting it back to him?