Basically they need to hit 350 subs per month for 3 months to hit Partner Plus, and then they get that 70/30 split for 12 months or $100K, whichever happens first, regardless of sub numbers.
I'm curious what happens after 100K. I imagine they'll have a separate contract with private terms after that. It would seem shitty to drop back down to 50/50 when you start bringing in more money.