The argument is almost as old as movies themselves: do motion pictures encourage people to act in a certain way? Do films that depict prolonged or detailed violence encourage people to engage in such acts? Do movies that depict rape convince some that it is fine to commit sexual violence? Do films that feature racist themes and characters encourage imitative behavior and attitudes?
The list goes on and can include any anti-social acts imaginable. Surveys conducted over the years vary, but generally come down on the side that seeing something in a movie will not encourage imitation from the vast majority of people.
Those who disagree with such conclusions often point out that children do not have the experience or judgement to avoid the temptation of certain activities in movies. Smoking has recently come up for criticism in this regard, with opponents recommending that any movie depicting tobacco or marijuana use receive the minimum of an R-rating (under 17 must be accompanied by an adult guardian), even if none of the film’s other content reaches that level.
The Motion Picture Association of America, which rates movies in the United States, does automatically give motion pictures depicting drug use a minimum of PG-13. There is no official policy regarding smoking, though it is sometimes included in the content warnings that accompany those ratings (movies with period settings and people constantly puffing away sometimes receive the humorous classification “historical smoking”).
My take is that children are far more likely to be influenced by what they see in everyday life, which is in their field of vision and imagination for much longer than a motion picture. If the parents or siblings smoke, it seems far more likely to me that others in that household will adopt the habit. Blaming movies for lapses in parenting and/or personal character seems like a cop out.