Anyone correct me if I'm wrong, but I'm pretty sure the only revshare is between one user and itch.io itself and of course game bundles. I do believe I had a friend forever ago who had a buddy find a work around. They essentially had a revshare games bundle, both uploaded and submitted the game but with (dev1name) and (dev2name) tacked onto the end of the game titles. That way if anyone bought the bundle would have the income split and sent to each dev. But that was forever ago, not sure if itch.io has a better way to share revenue between multiple contributors to a game or not, @.@'
That being said, even if itch.io doesn't have a method paypal or patreon does, i believe paypal has something called "collabpay": https://collabpay.app for like $20 a month for up to 3 contributors. That seems to do what you are thinking, though never used it myself so no clue, @.@'