No, the President has not needed and does not need Congressional approval to examine CIA files. The National Security Act establishing the CIA specifically exempts the President and Vice-President from constraints placed on dissemination of classified information. The rules regarding such dissemination were established during the Truman Administration and have remained, essentially, intact since. As the proprietor of intelligence information, the DCI implements the rules regarding dissemination. Although the DCI could resist turning over the info to the President, such refusal would be frought with career and political problems.