Had a massive heart attack and breathing difficulties. What is wrong? Related to chronic smoking?

I have a brother inlaw who is 67 has been a chronic smoker and heavy drinker . He is now in cardiac failure with 20% heart function I don t know what that really means.20% less blood being forced through or only 20 blood ejecting? the heart or 20 less muscle contraction? He has had ascites drained from his abdomen and plural fluid drained too. 3 years ago he had a massive heart attack and had a triple bypass and resumed smoking a year after his surgery. he is thin greenish blue looking cannot walk more than a few steps cannot bend to tie his shoes without breathing difficulties. He does not want nor is eligible for a heart transplant or an assist device. Aproximately how long can someone live like this? My family is pretty much uneducated and does not understand much about the body or what the doctor is telling them.