Well I don't pretend to be a girl, but i'm not proclaiming to be a guy either. If ppl assume i'm a girl based on the toon I play on, I really don't care. I let them think whatever they what, often playing along just for the fun of it.
Besides, the character I play on is Female (not all of them ofc) so ofc ppl will adress me a she/her, based on my character.
And ofc, I prefer to them in similar ways, if the player plays a Female, I call that player Her/She, and if it's a male, Him/He.