The payout procedure for the Unreal Engine Marketplace can be found in the Seller's Agreement.
"Epic will pay to you the Purchase Amount for Digital Rights sold by Epic to Customers, less any applicable withholding taxes. Epic will pay such amounts to you on a monthly basis (45 days after the end of the calendar month following transactions) by electronic funds transfer so long as the total amount due to you is at least $100.00. However, in no event shall Epic withhold any amounts for longer than one year. If Epic incurs any Automated Clearing House (ACH) or wire transfer fees, bank fees, or other charges to transfer to you the amounts payable to you, Epic reserves the right to deduct such charges from the amounts paid to you. Epic bears no responsibility for any wire transfer fees, bank fees, or other charges incurred by you. All amounts stated in this Agreement are in United States Dollars."