If they contact support, the gift email can be reassigned.
Viewing post in Friend sent a gift to a wrong email
I need a ticket ID to look up the request if you want me to handle it now. Keep in mind that it’s Christmas eve today, so our support team is not working. If it’s a critical gift then they can purchase the item again, and we can handle a refund on the mistaken purchase later in the future when our support team comes across the ticket requesting a refund.