Every boss or company must have its own rules, and they will not interfere in the household life of their employees unless the employees tell and ask for solutions. But if an employee is sick, the company will help by providing facilities that employees can use. But if it is a gambling addiction problem, not all companies will be able to accept it. Many companies will fire the employee immediately and not give them a second chance to start over. But indeed, gambling, drinking, and having an affair are things that our companies or employers don't want.
Make sense, and in each company they have rules that needed to implement, company owners or those who have higher authorities around can do this kind of actions, if duty calls them to fire someone in the sake of protecting their company, there's no excuse or exemptions, unless the person have that good character references and the company still believing that the person can change by means of rehab.
Gambling addictions can be cured if the person itself is willing to change his way. Though there' are a lot of open opinions about this, the take will be in the hands of the higher authorities.