Hi,thanks for query.I am sorry dear you may not be comfortable with answer but no,this is not possible,one can not have smell of a cigarette which was smoked 5 months ago.The smell cannot last this long.I think he is smoking
at present also.Bad breath
could be there due to poor oral hygiene
and give rise to bad smell but not of cigarette.Please discuss this with him with cool head and try to explain him the disadvantage of smoking.You can even take help of a doctor for this.
wishing you good health.