“pay to win” is an aspect that can be attributed to a game, not to a character
so no, Illari (and any other character one cares to name) is not pay to win
that said, the game being known as OW2 is a game that is pay to win by definition in part because of the existence of paywalled characters like Illari…characters that paying players get immediate access to, and non-paying players do not get immediate access to