These two sites are made on different methodology -- one is for "tweets" -- small messages while other is a real social media. Possibly you could say FB can beat Orkut - and answer could have been Yes.
yes i think because , facebook is very user friendly and also its GUI is so acceptable for a new user that he/she fall in loves with the overall site. also there are different new other features present on FB other than twitter.
the latest I heard about this was that twitter was going down... though the same was with facebook... people are getting tired of both... the question is, which one goes down first... that seems to be the competition