I haven't read much about it, but I have the feeling that all gambling sites just continue to accept Russian gamblers and that this has not been banned at all. There is also no legislation for it. Those gambling sites are located in countries where there is little control. And if you were to introduce a ban, Russians would also be able to gamble at other sites. It generates too much income to put a ban on it I think. That's not so easy.
Russians as average has small salaries except a few oligarchs who control 99% of the wealth there so there is not much income to be lost for a gambling company but I agree there is no legislation and gambling companies do not care from which country a person is.However big exchanges like Binance has banned a lot of Russian accounts so far but I don't think there will be a rollover into online gambling sites,better to say crypto sites because sites like bet365 it will be difficult for any Russian civilian to keep accounts there because as far as I know their headquarters are in Europe,and Europe has put sanctions against Russia.