I definitely agree with your point, Hellon, about the picture not affecting if you're going to smoke or not. If the craving is that bad, well, advertisements or such won't stop. I don't think it's a lack of information in this day and age since teenagers have access to the Internet and know about the effects of smoking, second-hand smoke... not to mention the campaigns and PSA's on tobacco use as well as anti-drug ads.
What I've found to be harmful on-line (mostly through tumblr, which I purposefully stay away from now) is a heavy focus on "aesthetics" and romanticization of harmful things, such as addictions. Addictions are set in a light of "beautiful tragedy" and tumblr often glorifies and justifies it. I noticed this with mental illness as well. When I joined tumblr during college, I would look at very dark photos/posts about depression. It fueled my own isolating, damaging thoughts. It all seemed tragic, but in a sort of "pretty" way. That's a seriously warped perspective.
I think if anything, seeing a person with the cigarette in their mouth would have more of an affect on someone than just a picture of a cigarette and flowers, or a cigarette and another object (like in my profile pic). But again, who can really affirm that? I think it's about perspective, if you grew up around adults who smoked constantly, etc. I've seen some photography done with cigarettes, pills and other harmful things used as commentary on society, so it can be used tastefully in art to portray a message.
Going off of what Larry mentioned, there is the history behind smoking in movies and tv shows, how it was socially acceptable and how in almost every scene you could expect to see actors and actresses sharing that moment. It became the "norm" if you will and viewers noticed the casual relationship between the person and smoking, as they would go about their day.
I personally don't find photos of cigarettes harmful since almost everyone who smokes is aware of the risks and holds control over their body. Addiction is addiction and it isn't going to be cured by simply banning advertisements or censoring media. Wouldn't that also be an attack on free speech? I used to chain-smoke a few summers ago when I was trying to not self-harm. In a way, smoking was an alternative way to harm myself in the long run and maybe that appealed to me. It helped when I became anxious and wanted to hurt myself in more immediate ways. Many people I know smoke as a coping mechanism or a way to distract themselves, relax or get through a tough moment. It fills the empty space in your day or night and many people like the feel and touch of actually holding something in your hand. It gives them something to do and a way to exhale from the rush and stresses of life.