Damn that's a huge sum of BTC. Congrats man. You got such an amount which I can't imagine to win even lol. Bitcasino is a long existing in this business and I believe they will be following their previous and will come with ethics.
5.8. If you win 50 bitcoins or more, we reserve the right to pay a maximum of up to 50 bitcoins per week until the full amount is settled.
No matter if they pay partially as long as they agree to pay the whole amount. It makes sense why they want to pay partially.