Trying to find more info by googling it but can not find a news of a big win (around 11btc) at 7bitcasino. I have read many others big win on that site but not for this one. Usually some review gambling websites will use such big win to make a good advertisement. I wont believe it till there is a valid proof to support this claim.
I would call this advertising, is there cheaper and better way from this one? Newbie account, always newbie account, let's not forget that, comes here and wrote about some huge win, but proofs will come later, if ever. Now we all read about it, talk about it, we check that site where someone had some huge win.
People win big, but those people who win big don't go around bragging about it. Always advertising, sites have strange ways to advertise themselves. I will not believe in this even after they bring some proofs on the table, today its easy to counterfeit everything, couple screenshots doesn't worth a lot nowadays.