Gambling is similar to taking drugs. Science has proved that gambling and drug abuse have similar brain waves. I suggest you use the attention transfer method. For example, when your father is at home, you should talk to him more, or let him do things, preferably things that you seem impossible or try hard to do, so that he will have a sense of accomplishment! Will weaken the psychology of wanting to gamble. In fact, most people gamble because they are bored or have nothing to do.
If the above method still doesn't succeed, you have to replace him with another extreme, and find something that can make your father photogenic and harmful, such as letting him surf the Internet and let him be obsessed with which online game, so that he can at least stay at home every day. Don't use this method unless it is very serious.