The whole new tier, will be 9518 seats. Of that circa 8000 ish are additional new seats, the rest are existing being absorbed into the tier. Excluding Tier 1 below which is unchanged.
That includes 456 skybar seats and 120 hospitality seats outside the hotel rooms looking onto the pitch. They are 'true hospitality', if you would. Thenrest id all general admission, that's 8942 GA seats. Including 648 GA+ seats at the bottom of the tier, which are hospitality-lite type seats, but could also well be season tickets as well just a higer offering.
However, of that, I have absolutely no idea whatsoever what portion will be season tickets and what not. Some have mentioned it will all be flexi-gold. The club haven't said anything publicly, but even at 51% as you note if 'majority' is a true allocation, that's still around 4.4k potential season tickets to allocate, once you exclude the hospitality.