Not everyone farts everyday including myself so there's really no set amount of farts someone farts in their lifetime.
But I do remember reading somewhere online that for someone who farts 14 times per day and that person lives to be 81 years of age then that person would fart 517,387 times in their lifetime.
Of course that is for those people who may fart that often but for those who fart less and sometimes go days or weeks without farting then they would fart a lot less.