Ah okay. I thought you meant the object "smoke", not that you are talking about the smoke of a campfire. There was a technical object Smoke in the Java Version that gave you 2 or 3 different types of "smoke" - even if you had no campfire. Just the smoke itself. That is not yet implemented in the Unity version.
The objects from Java do not get transferred to Unity as they seem to be too different. But however in Unity you can resize the objects. You can also hold them in place with ctrl key and then use arrow keys to move them inside your wall/floor/whatever.
I also was thinking he was talking about the smoke only object, I was like why blueprint this oO so your not alone, in the unity version you can resize the fires so small you can hide them in the chimney for a smoke effect, only problem is the light from the fire goes through the blocks and reflects on your roof oO not a big deal and that problem will be fixed so I read on another post.