Are smokers or obese people not eligible for coronary artery bypass surgery?

No: They are higher risk but smoking or obesity is not contraindication for coronary artery bypass surgery.

Per se, no one is: Excluded. Risk analysis is done for everyone who needs cabg. Risks will always be a reality. But managing risks is the challenge to the "heart team", that includes the patient.

CABG: No, they are still eligible, but their risks of surgery are much higher. Obesity and smoking would exclude one from getting a heart transplant though. Also, smoking would (at least in my practice) exclude you from having weight loss surgery.