As everyone else has said, they are not available in the parks, but are available at the resort gift shops hidden behind the counter, you must ask.
We have pretty decent cigarette prices here at home, so I always just bring two cartons with me. (Not that I smoke that much, but if a pack gets lost or wet, etc.) I always bring two packs into the parks with me. Nothing worse than losing a pack and having to leave the park, go all the way to a resort and find the store for a pack of cigarettes.
One time I had the most frustrating evening at the Magic Kingdom. It came a DOWNPOUR. Everything got soaked, even my sealed pack of cigarettes in my daypack.
Even if the cigarettes hadn't gotten wet, it was raining so hard nothing would have stayed lit anyway. I finally made it over to the Polynesian, bought a pack, (Almost $6.00 with tax), then got outside, to a designated area that was covered somewhat (still pouring) and realized my lighter was soaked too, so had to get back inside to buy a lighter.
After all that I didn't feel like heading back to the park, (was almost closing time anyway). Called WDW-Dine, got me a seat at Ohanna's and had a nice dinner.
Carol