They will not pay it... And isn't their fault is the fault of the users for play in the worst casino they find.
I'm really sad about OP because the win was really huge, to bad you don't win that amount on a trusted casino like Bitdice, Luckybit or Just-Dice...
Next time verify how much has paid the casino in the past to a single user, that's a nice way to know if you can trust them.
Lets not judge too early, we should give a support to OP by giving him a hope instead of giving him a early frustration.
171btc is absolutely a huge amount of money and I believe any sites will do double check for such huge win before releasing it to the lucky user.
If bitcasino will not pay this huge win, I believe it will be the end of bitcasino.
Lets wait and see on how bitcasino will handle the situation, personally I hope this user will get what he have just won.