OP, the girl looks pretty, but exploiting female body so much in the industry is not a good thing to do. Firstly, you are contributing to the general tolerance to violence and objectivation of the body (women are people, not some attractive things). Secondly, I bet a lot of women and liberally-oriented men will be lost from your potential audience this way. Thirdly, as betwrong mentioned, cheating might not cheer the customers up.
Nowadays, both man and woman body used in promotion in different industries ! those men and girls get money for doing that, it's their job. Another thing, most casino that I know use this kinda method which means, there are statistics and data that make them use women. Finally, let's not forget that casinos at the end of the day target specific type of people, those whom have problem with using women for that business most likely would have problem with gambling in first place.