It might be about isolation. Smokers are sometimes ostracized in certain social settings. In the 'the smoker short story', perhaps the main character is isolated because of their smoking habit, and the story explores their feelings of loneliness and their attempts to fit in or find acceptance.
The main theme could be addiction. Smoking often represents an addiction in literature, and the story might revolve around the character's struggle with this habit, how it affects their life, relationships, or personal growth.