What is the life expectancy of someone with chronic emphysema?

Difficult. Calculating life expectancy in COPD is very challenging. Limited life span is found in patients with chronically elevated carbon dioxide levels, frequent exacerbations of the disease and low body mass index. Given you an exact survival percentage is usually not possible.
Variable. This is very difficult to answer. The severity is important as are other health problems. As the disease becomes more severe the risk of death becomes higher. Actually, most patients with COPD die from cardiovascular disease or infections.