What is the percentage of dying skin on smokers having a Facelift?

You are referring to the feared complication of skin slough after facelift surgery. As you imply, smokers have a significantly higher risk for this problem to arise. The exact risk depends on multiple factors including facelift technique: It can be minimized by using a deep-plane facelift but the risk is still higher than in non-smokers. Numbers found in the literature range from 3% to 20%. 

If you have skin necrosis and slough YOUR incidence is 100%. We know there is a very significantly higher risk in smokers and our best medical advice is to prevent any potential complication you can. Stop smoking! It not only raises the risk of necrosis but slows healing, increases your risk of infection and lung problems. Most facial plastics surgeons will NOT operate on a smoker. Your primary care physician can advise Wellbutrin or Chantix, both of which can be continued during the peri operative period. Nicotine replacement is NOT acceptable.