First, let me say that it takes someone who is sick to first and foremost, realize and accept that he or she is sick, before he or she can proceed to visiting the hospital for possible tests and medication based on what the doctor found out through the test, to be the ailment the patient is suffering from.
What am i saying in essence?, A gambling addict who have refused to accept that he or she is addicted, helping such person can most of the time be just you wasting your time, because addiction have everything to do with the mind, and if the gamblers mind have not come in agreement with you that he or she is addicted and truly needs help, trust me when i tell you that, trying to force help on such individual is a waste of time.
Better to leave such a person to go on with whatever he or she is doing, hoping that one day, the person will indeed realize that he or she needs help, this is when your help can indeed yield good result in the gamblers life.
This is probably, the most frustrating aspect of any addiction, every single person that has ever known the addicted can tell they have a problem and they are in a desperate need of their help, but if they cannot take the first step and admit they have a problem then there is nothing anyone can do for them, and if anything trying to do so will only create friction between the two of you as they will think you are trying to take decisions over their life you have no business taking.