This is a great question. In short, we could say subtract X years for chewing/smoking tobacco, subtract Y years for drinking lots of alcohol and subtract Z years for eating fats.
However, for anybody knows, she could have more problems if locked in a sterile room, being fed nothing but rabbit food and nuts. I know some taxi drivers who consume a fair amount of beer on their days off, and they eat take aways, they also smoke. They had bypass surgery over ten years ago and are doing great. Me? I followed all the rules and mine lasted 3 months.
According to the bible of dieticians and cardiologists I should be running the london marathon every year. A close friend of mine died at 38 from lung cancer (smoking), but all my grandparents smoked unfiltered cigarettes from the age of 14. They used to spread pure fat on toast and eat lots of it. They all lived to be older than 90. There is no way anyone can make accurate statements on your Mothers outcome, we would simply have to run a lottery. Nature doesn't allow predictions, there are always plenty of exceptions, we can't even predict the weather accurately.