Here’s a scan of the Montreal Gazette relating the discovery of Champlain Baptismal registry which proves Champlain Birth year is 1574.

Note that both french and English version of Wikipedia about Samuel de Champlain up to now (June 2020) either show the wrong birth date of Champlain or used the baptism date as the birth date. Up to now, no special information has been found about on which specific day and month he was born, the baptism occurring in August, he is only certainly born that same year.