Is it possible to get oral herpes from sharing a cigarette from someone who has it but had no active breakouts at the time of sharing the cigarette?

Yes: Yes. Oral herpes is contagious. It is not safe to smoke cigarettes, or to smoke anything else other than brisket, ribs or chicken. Smoking cigarettes means inhaling the toxic stuff of burnt organic material and its added chemicals, whatever they might be. It is even more dangerous if a woman smokes and takes estrogen, such as in birth control pills and other hormonal pills, creams, or patches.