In order to play GTO in the spot that you mention we need to make our opponent indifferent between calling and folding with his weakest bluffcatcher. Indifferent because if either calling or folding has the higher EV he can choose to call 100% or fold 100%. When we are properly balanced and our opponent either calls or folds more than he theoretically should we will gain EV from his mistake. In this case it is also irrelevant for us how often our opponent will fold since he can not unilaterally change his strategy to increase his EV.

Because our opponent gets 2:1 on his call here we need to have 2 value bets for every bluff in our range.

Sauce covered this exact spot in this video:
http://www.runitonce.com/pro-training/videos/toy-gaming-part-2/

If you risk pot to win pot, you need to win 50% to break even, so Villian needs to defend 50% of his range.
Because he's getting 2:1, he needs to be right 33% of the time.
And because he needs to be right (you're bluffing) 33% of the time, you should have a value/bluff ratio of 2/1.

This helps:
http://www.runitonce.com/chatter/gto-simplified/

Thanks for the replies! So if we know he gets to the river with a wide range in which 40% of his range beats our value hands and 60% of his range loses to our value hands, then his strategy will pay off a GTO strategy versus breaking even against it?

Further if we knew this information about his river range, could we play explotatively vs him to maximize our EV by changing our value:bluff combos or bet sizing?