The Tao Te Ching's own textual history is genuinely contested: some accept the traditional account of a single sixth century BCE author who served at the Zhou court, while most modern textual scholarship reads the work as a compilation of aphorisms and verses assembled from multiple hands over generations, closer to a fourth century BCE finished form. No biographical source for Laozi predates the legendary accounts collected centuries after his supposed lifetime.
What would resolve this New early manuscript evidence bearing directly on authorship and date of composition, of the kind the Guodian and Mawangdui bamboo and silk manuscript discoveries have already partially supplied for the text's transmission history, though not yet for the question of a single author.
OpenSinology, paleography, textual criticismStanford Encyclopedia of Philosophy