Q:

Is "otaku" a male term? 

I want to determine if the term is gender specific.  Thank you. 

A:

No, it's not.  There are many female otaku, too.  Among those who understand the modern otaku culture, otaku is a fairly gender-neutral term.  For example, about 35% of attendees of Comiket are female. 
That said, otaku is a slang word with a relatively long and complicated history, and it used to have a very derogatory and narrow meaning.  I imagine there are still many people who believe otaku-like hobby is only for males.