It's pronounced Ma-Kai-Yuh. It's a biblical name that means "who is like God" the J spelling is the Hebrew spelling and can be used as a boy or girl name.
I had no issue pronunciation, this is also a nice name. I prefer Micaiah, as the J is probably confusing for those who do not know the history of the name.
Re: Spelling of a girl name.
The j is confusing to non Hebrew speakers. Hell, even without the j it's confusing to non Hebrew speakers.