It is generally accepted over the web by majority of people that it is Satoshi and there is even a user name on this forum carrying such title as the founder, this I also found when I was equally curios about same thing as you. Whether that argument is true or not, I guess we all have to accept the report of people that have been here or in the crypto-world right before many of us and they have agreed that he is the one then who am I who joined few months ago to disagree with that fact?