My dad was diagnosed with emphysema we he was 36, and he is 50 now and still smoking. how much longer does he have?

Hard to say: Difficult to say without more information, but he is greatly shortening his lifespan as well as the harming the quality of his life with continued smoking. Quitting is the single best thing he could do for his long term health.

Variable.: The progression of emphysema is variable from person to person, but continued smoking probably increases the risk of more rapid lung loss. Also, most people with COPD actually die from cardiovascular disease. Quitting smoking is essential for your father as a first step.

Hard to say...: COPD progresses at a different rate in different people so it is difficult to predict how long an individual will survive. However, if he continues to smoke, it will progress faster and cause more symptoms, including more shortness of breath. He may even develop lung cancer and die of that. He needs to quit asap.