Jio cinema follows the same policy like Disney+ Hotstar when it comes to number of screens. It will log you out of the 1st device when you exceed the number of devices included in ur plan. It's not the number of simultaneous streams like Netflix considers irrespective of number of devices logged in using the same id.
So if they launch a 2 screen plan and you have 2 TVs in your house and your mobile then only 2 of those will remain logged in at a time.