Since your family member is having a single by-pass only one of his coronary arteries is blocked. Being a smoker leads to coronary artery
disease but I don't think it will complicate the surgery however the recovery will be more difficult. After the surgery, we tend to get some fluid build-up in the chest cavity and the lungs. Some coughing is required to clear the lungs. I have had a triple bypass and I am still recovering. It can take 3 -6 months to recover from the surgery. The usual hospital stay is 5 - 6 days. The doctors will strongly suggest that the smoking
stops. Good luck.