I am unsure how this question is meant. The trivial answer is, that the platform does not matter. A successful indie game will be on many game platforms. If you exist on Itch alone and do no marketing and have no "viral" game, the game will be unsuccessful, no matter how good it is.
And going "viral" on Itch is hard. It's not impossible, but if one could find out a recipe for that, it would not be hard. And by viral I mean that word of mouth is enough to market the game.
What does especially well on Itch specifically, are things that are not seen on big game platforms. That covers things like games that are still in development. Fringe and nieche topics. Special interest. Low budget. Even horror can be considered such, as it extra popular on Itch, but not so much elsewhere. And yes, also the gay furry dating sims mentioned above. While Steam does have games with lgbt topics, they have exactly one tag for that. lgbtq+. And there is no furry tag.
All that being said, there is one point to make. An important point. Just because things do well on Itch, does not mean that if you create such a thing, it will do well. Horror dominates the first page of popular games. But there are currently 77000 horror games on Itch. Creating a horror game will not make that game appear in the top pages, just because it is a horror game.