He can availed gratuity even if did not complete 5 years of service. Only thing is he should complete 240 days in lasy year, i.e. 5th Year. Apart from this if management decides to pay the gratuity even after 4 years, can be possible only sanction of trustee is required, this amount is paid from the funds available with the provider/ or the fund manager. This is ofcorse in a normal conditions of employee departure