I think that a casino does a lot of promotions at Christmas time won't have many customers
I have a different experience. I remember how last year Duelbits ran Christmas box event. Every day users came, open a box a got a prize (1/5/10 coins or 5 free spins if I remember it correctly). Users discussed their results in duelbits topic rather lively. That all created a feeling that more than usually users visited casinos page. I think they also got lucky tickets event, where users get tickets when they wager 100$, so users used free box prizes to wager. All it all duelbits was kinda busy Last Christmas
I gave you my heart 