It use to be Cloudbet but they are defunct as they are not paying their players now when they win and do not allow US residents to use their site anymore.
They use to match your initial deposit amount upto 5mbtc from when I used them a couple of years ago.
But now it is Sportsbet.io who are doing this but not upto that amount with the price of bitcoin being 10x more than what it is worth since then.
I think they are doing the match upto 1btc on your first deposit.