If you work in a place where you might suspect that your boss is an alcoholic this can open up a whole different can of worms for you and the environment in which you find yourself working in. The first thing you need to understand is that even if it might be true, this isn't exactly the kind of thing that you can easily approach or accuse someone of, especially your employer. With an employer that may or may not be one, the accusation could end your employment and you could be out of work starting a new job search.
As much as you might want to, you should never consider trying to save your employer from his alcoholism. You should not do this because more than likely you are do not have the skills or any kind of training to do so. Only a professional with solid training in addiction counseling should ever attempt to help someone with any kind of addiction. Trying to do something like this on your own is not going to help and in most cases it causes friction, distrust and resentment against you by the person who is the alcoholic.
If you believe that your boss is truly an alcoholic and that this is causing too much harm to the company you are working for, then the best thing you can do is to get a hold of someone at your local AA or Al-Anon office and ask to get some help. There are a multitude of different places that work with alcoholics and their addiction, these are probably two of the best places to begin learning about how you can work with and maybe even get some help for your employer. You can easily find a location in your area by either going online or looking in your phone book for one of their locations.
The worst thing you can do however, is to confront your boss about your concerns and suspicions. More often than not they are going to look you straight in the eye and deny all of it and will act insulted that you would even suggest that they had some sort of drinking problem. It doesn't matter if you are correct and right on about it, doesn't matter if you have smelled alcohol on them numerous time during work, you are more than likely only jeopardize your own job and on top of that you will probably end up in a huge dramatic scene. Because drama is part of the life of an alcoholic. It's their way of blaming everything on everyone but themselves.
It is important to remember that there is only one person that will be able to truly help the alcoholic stop drinking and it is simply the alcoholic. They must truly and honestly want to stop, or they never will.