What is the process for determining if an infinite loop will be a draw?
What you are describing is a loop of mandatory actions. Unless someone breaks it, the game ends in a draw.


  720.4. If a loop contains only mandatory actions, the game is a draw. (See rules 104.4b and 104.4f.)


That said, noone is forced to break it even if they could.


  720.5. No player can be forced to perform an action that would end a loop other than actions called for by objects involved in the loop.




You seem to be asking how to get the game declared a draw. 104.4i allows the players to mutually agree to a draw.


  104.4i In a tournament, all players in the game may agree to an intentional draw. See rule 100.6.


If the other player refuses to accept, you can't just keep passing, because that would be Slow Play.

That leaves the option of creating a shortcut. The active player should propose passing until the loop is broken (or until they get priority in the next phase/step for a loop that doesn't span phases/steps). If the opponent accepts the shortcut, the game is officially a draw because neither player ever gets priority again.