There is obviously a very big difference between a celebrity and an influencer, not every casino or gambling platform can afford to become partners with celebrities whether they are from sports industry or film industry or music industry, because a partnership with one of these celebrities would cost the casino way higher than having multiple influencers promote their services but the impact of all of them combined won't be enough to compete with one of the celebrity's.
Even among influencers, those who have a lot of followers and people watch them very often and they have a lot of views and interactions on their videos and live streams tend to charge more money for promotions than those influencers who are relatively new and has less followers or even if they have many followers but they don't get enough views and interactions.
Also, not many celebrities want to work with casinos because they think about the reputation it has built. And also, they don't want to see their fans playing gambling and getting addicted. But if it's an influencer, the casino can offer them cooperation, especially if the influencer has a lot of fans and often gambles. This will make it easier for the casino to offer the influencer to accept it.
But the casino also doesn't offer cooperation to just any influencer and only chooses influencers with a lot of followers so that lots of people will see videos from that influencer. And usually, if the casino has found the influencer they are looking for, the cooperation offer will last a long time because each casino and the influencer can both benefit.
Yeah right, I rarely see them go for gambling promotion, that's because maybe they think about reputation like you said. But apart from all that, of course I see more of them (influencers) who are more active on social media and more interactive with their fans. I actually don't want to differentiate between celebrities and influencers, but there is a slight difference between them.
They (what we call influencers) are interactive with their fans which is a distinct advantage, because someone who follows them on social media will feel closer and after that they will definitely want to try something that influencer does.