Did Satoshi ever acknowledge that his name was a pseudonym?
This post is the closest to an acknowledgement that is was a pseudonym as can be found:

"I am not Dorian Nakamoto."

http://p2pfoundation.ning.com/xn/detail/2003008:Comment:52186

http://www.forbes.com/sites/kashmirhill/2014/03/06/bitcoin-creator-returns-to-internet-to-say-i-am-not-dorian-nakamoto/#613499a67f43

The above quote was made in response to the Newsweek story falsely outing him as Dorian Nakamoto (birth name Satoshi Nakamota).

http://mag.newsweek.com/2014/03/14/bitcoin-satoshi-nakamoto.html