I am not sure if a hotel accommodation will be provided for you.
Why do you have a 13 hours stopover in DXB? The normal connections are around 2 to 7 hours for JFK-BKK flights...
I think, if there are shorter connections possible, they will not give you free hotel accommodation.
Otherwise you will get a hotel voucher at check in at JFK.
I never got a written confirmation for my accommodation in DXB because of a long connection time, but always got the voucher at the departure airport at check in.