"how many interviews did you go through for a Big4? I'm done with the second one. How long does it take for them to email/call you back? The interviewer said to wait for an email. It has been two weeks and I want to find out if I passed or failed."

Was your second one an office visit interview?  My first one was on Campus with a Manager, and my second was an office visit consisting of 2 interviews:  1 with Manager, 1 with Partner. 

I received a phone call in 2 weeks with the news.  I think this varies greatly depending on which office and how many applicants are competing for a spot.  I don't think its unheard of to even wait for 1 - 2 months.

Good Luck!