Ok I know some of the cast smoke but i dont know who...

I hope this helps-:)

I Know For Sure That Edward Cullen(Robert Pattinson)smokes, as I have seen several pictures of him smoking.

Edward Cullen:(Robert Pattinson),Rosalie Hale: (Nikki Reed). I don't know if the others do.

edward
bella
emmett
rosalie
jasper
carlise
those are the ones ive seen i think they all smoke except alice and jacob

hope that helps

None but i think Catherin Hardwick does

The ones who smoke are:
Edward Cullen (Robert Pattinson)
Isabella/Bella Swan/Cullen (Kristen Stewart)
Rosalie Hale (Nikki Reed)
Carlisle Cullen (Peter Facinelli)

They are the ones that for sure smoke, but I've seen also pics where Emmett Cullen (Kellan Lutz) and Alice Cullen (Ashley Greene) are too.
I'm not sure about Emmett (Kellan) because in an interview he сказал(-а) that smoking let Ты a bad breath and yellow teeth, so he was probably wanting to prove it.

PS: Neither Jasper Hale (Jackson Rathbone) nor Jacob Black (Taylor Lautner) smoke :p

Hope these helped =D

Really sure Kristen Stewart and Robert Pattinson do.
As far as it concers to Nikki Reed, she was asked about it, and she herself stated that she used to smoke as a teenager, but she doesn't any more.
Taylor Lautner definitely doesn't & that's all I can tell.

But those pics from New Moon set are kind of old, lots of things have changed since then xD