The key parameter which can be controlled by the casino and which affects the casino’s income is the winning payout (let us call it W). For each game and each bet the casino calculates the user's winning chance (let us call it P) and determines the victory payout as a relation in the form of
P * W = const
House edge, or the casino advantage, is set by the constant in that relation: for example, for a 1% house edge, the relationship would be P * W = 0.99.
This relation guarantees the casino’s income due to the fact that it is basically the expected value of the user’s win. In simple words, this is the part of the user's bet that he is most likely to take for himself if he makes a large enough number of bets. By maintaining these parameters in such a ratio for each game and bet, the casino will always win if the players make a large enough number of bets.
Casino advantage value can be initially set by the admin and can be later increased by the DAO to gain higher income, however it should be taken into account that users can always calculate this value by themselves and hence seeing lower payouts might deter them from playing.