From whats been posted before on this forum im under the impression they either have to pay the winnings or refund the deposits.
Like I said, Ive been in this situation before on Casumo when I deposited several hundred from my wifes card and hit a massive win, casumo werent happy about it and made me verify her details and then approved the withdrawal with the warning of not to do it again.
Its possible but like I said, dont hold your breath.