My parents, heavy smokers, smoked until almost the end. Mother had a severe stroke at 70 and lived as an invalid for 5 more years. High blood pressure from smoking didn’t help. My father also died at 75 of COPD (smoking) and a weak heart. Not sure when he quit if he ever did.
I have some very long lived genes on my fathers side and I am convinced that if he had not smoked he could have been like his aunt and been the oldest person in the US when he died. His aunt lived to be 115 years and 9 months.
Of course they were WW2 era people and they almost all smoked.
I had a granny who lived to be 103, and my father lived to be 93. I plan to croak around those ages, and I have to way to go yet.