If someone has stage 1 COPD and still smokes, how long will they live?

The question of smoking with COPD and lifespan is difficult to answer because the stage of COPD is only one factor that determines how long someone with COPD can live. Roughly, just looking at lung function (which determines the stage of COPD), the survival in stage 1 COPD is probably not much worse compared to those without COPD, particularly in the short run. Also, for continuing smokers with all stages of COPD, the survival over the next 5 years is probably only slightly worse compared to those who stop smoking. Beyond that there is a widening difference with increasing deaths in those who continue smoking compared to those who stop smoking. For example, 10 years down the line, roughly 80% of those who quit smoking are still alive, compared to only 55% for those who continue smoking.

Other factors (besides stage of COPD and whether someone continues to smoke) that should be considered when looking at lifespan with COPD include: the oxygen level, the exercise capacity, how much shortness of breath there is, how quickly the lung function is getting worse, the body mass index, nutritional balance, and whether there are other diseases that are often found with COPD (such as high blood pressure, heart disease, diabetes, or kidney problems)

One important point to know though is that studies have shown that there is always an advantage to quit smoking, no matter the age. In other words, it is never too late to quit.