Quote from that site :- "
* Research also shows that cigarette smoking probably damages cells in the testes - the cells that synthesize testosterone. Testosterone levels within the body govern the muscle growth process from training. Thus, smoking may well hinder optimal testosterone production and interfere with the body’s capacity to build muscle."
Of course the major side effect of smoking is death. That's not good for your muscles either lol 
I doubt smoking significantly 'kills' muscle cells, enuff to notice that is. But the oxygen depletion can't help eh!
If you'd like an excuse to keep on smoking tho check out Markus Rhul shopping on youtube, one of the biggest (retired?) BBers out there and he's chugging away like a SOB.