Did Gautama Buddha cease to exist after death? After death did Gautama Buddha ceased to exist? Or  does he still exist?
This is exactly one of the topics (i.e. whether a Tathagata exists or doesn't exist after death, or both) which the Buddha "didn't declare" -- see the Cula-Malunkyovada Sutta (MN 63):


  And why are they undeclared by me? Because they are not connected with the goal, are not fundamental to the holy life.