i don´t think あなた can get a perfect answer...i mean, i got most otaku フレンズ that are girls..but again..you would have to take the biggest otaku test ever to find out^ ^(sorry about my bad english!)
I'd say that there are もっと見る male Otaku, but then again i've only ever known one female Otaku and she was my cousin (and the sole reason of how i got into this)
Wowee.. I don't know... Even if I generalise it to one series, like Naruto.. I kind of know the same no. of fans.. Maybe もっと見る girls, because I'm a girl and I meet もっと見る girls than boys in general..
... あなた could plan out a world wide Otaku meet up which could be compulsory to attend..Maybe then you'd have a correct answer....