As things are, with my understanding of things, my answer would be a resounding yes. Later on, should the option to avoid lesbian content be added as the dev wish to do, then my answer would switch to "Yes and no my friend". Let's pretend someone would be interrested in a game where the main character is a female, but have sex only with men, then the lesbian tag could act as a repellant for such a potential customer. It then all comes down to the audience the dev choose to target and his/her marketing choices.
To be honnest it may even be better to offer the game two times on each marketing platform, one with the lesbian tag and one without, and see how each fare before eventually redirecting the minoritary one toward the more commercially interresting one. I guess that could have a negative impact too by making the game less less visible, but that would also dampen the impact of people not getting what they wanted, or more accurately getting more than what they wanted.
Not sure about websites policies regarding my last thought though.
Viewing post in Freshman Year (Demo 1.01) comments
It will definetly be easier to market once I have continued the game and no how the story will unfold throughout the game, right now I have lots of ideas to hopefully encorporate all categories but if this becomes to challenging I can tone it down. I may take your idea and release multiple versions to see what the audience would prefer but hopefully I can make it where the choices will determine sexuality. We'll see, thanks again!