I think an important factor is the data that the NU Ticket Office has about their current season ticket holders in Ryan Field's current premium seating options. It's hard to find solid info on this, but here is what I've managed to piece together:
NU website's description is in italics. The rest is what I've been able to figure out, mostly based on carefully looking at empty stadium photos and other sources.
Box Seats:
Box seats are located on the east and west sides of Ryan Field between rows 21-23. Box seats are outdoors and feature chair-back seating close to the action. This location is only available on a season ticket basis and sold in multiples of 2 seats.
8 sections have box seats (107, 108, 109, 110, 127, 128, 129, 130). Each section has 5 boxes: 3 with 4 seats (spanning two rows) and 2 with 8 seats.
Total number of box seats: 224
Wildcat Den:
“Den” seats are located on the west side of Ryan Field below the press box. These chair-back seats are open to the atmosphere of the stadium, but feature protection from inclement weather, above heaters, all-inclusive food and beverage, and private bathrooms. This location is only available on a season ticket basis.
Consists of the back rows of sections 228, 229, 230, along with the small portions of sections 227 and 231 that are located under the press box. The 3 center areas appear to be 4 rows deep, with 18 seats per row. The two smaller areas appear to be 4 rows deep, with 4 seats per row.
Total number of Wildcat Den seats: 248
Stadium Club:
Located on the west side of Ryan Field, the Stadium Club is a climate-controlled indoor club and seating environment which features soft, cushioned stadium seating, private restrooms, flat screen televisions, all-inclusive food and beverage options, and two bars. This location is only available on a season ticket basis.
Total number of Stadium Club seats: 325
I don't know anything about the current pricing and required donation level for any of the premium seating options, although I'm sure someone on this board might have some knowledge. The only other data point that I can offer is that I put myself on the wait list for Box Seats in July 2021 and have not heard anything back, so there is at least some unmet demand for that tier of seating. (although I think NU is being very generous in the term "premium" when it comes to Box Seats.)
My point is that I think the decisions on the number and pricing for premium seating will be informed by multiple data points: the survey responses, historical demand/pricing for the current premium seating options, and projections based on Welsh-Ryan ticketing data, to name a few.