Both of my parents smoke so I know how you feel about it...my dad is worse than my mom though...my dad still smokes really strong cigerettes...but my mom moved to the more slim and not as strong cigerettes and that helped her a lot...she only smokes about 4 cigs a day...where as my dad smokes about 10+ . It's hard to convince or make someone to stop such a habit...but it's not impossible...a lot of people have quit smoking so if they can your mom can too :P Just try be there for her and try explain to her what it's doing to her health and her body in the nicest way possible. Different people do different things to stop them from smoking a lot of cigerettes etc.
1. Chew gum
2. Drink water
3. Switch to a lighter ciggerette
4. Keep yourself super busy so you don't think about smoking
5. Relax as much as possible so you don't stress...smokers turn to cigerettes of course when they're stressed...
I wish you luck to help your mother stop :) I'm sure you two can do that together! It's going to take a while...and it won't be easy...but you can do it :)
Amazing book "the easy easy to stop smoking"
But it won't work unless the person kind of maybe wants to want to quit