traditional contributions, how do the taxes work?

Example:
Gary contributed a total of $50k 401(k) account. All of it was Roth contributions.
Gary's employer matched all of the $50k, but the match counts as traditional contributions.

Gary's 401(k) has grown in value to $300k. Is exactly half of this amount considered to be Roth and half traditional? If Gary wants to take $80k in distributions this year, can he take $50k in Roth distributions and $30k in traditional distributions (and since he's married filing jointly, that will be exactly equal to the standard deduction, so he won't owe any income taxes)?