If I were to hazard a guess, I think that there is a greater than 50% probability that Purdue will outdraw IU in viewership. My reasoning is:
1. They did so in the previous year if I recall the ND Nation correctly. Trends matter.
2. The B1G West seems to be very competitive and Wisconsin is not identified as the clearly dominant power. Thus, Minnesota, Iowa, Purdue and Wisconsin are being talked about as potential winners. More wide-open competitions tend to attract more interest than if there is one dominant player.
3. O'Connell is being talked about and getting some national publicity as the walk-on to starter story gets mentioned. QB is the most important position and people like the rags to riches story.
There are a lot of wild cards in the deck which creates a lot of uncertainty. Injuries can ruin a season. Remember when Sindelar (QB) and Rondale Moore (AA-WR) were injured on the same play and each missed multiple games? That is an extraordinarily rare play and really hurt a season's performance. Viewership is positively correlated with performance and a rash of injuries can harm performance in a big way.
Purdue gets to open the season in a nationally televised primetime game against Penn State on Fox AT HOME. I think that a great deal of the season's success hangs on that game. I think that PSU is in a downtrend but viewership lags W/L on the upside and the downside. PSU still has name recognition. If Purdue wins, that will get talked about a lot. That promotes viewership. I see a close game and favor the home team in a close game.
The early season, especially if they beat PSU, is favorable. Syracuse is on the road but not regarded highly. Babers is on the hot-seat. Then Purdue returns home for a second primetime game against FAU. If Purdue beats PSU, and does not drop an early-season road game in which they should be favored (as they have in the past, e.g. Nevada), they are then undefeated going into a second primetime game. That would stimulate viewership.
Next game is against a nemesis (Minnesota) on the road. Not primetime, but against another West contender. A game between contenders is normally viewed as competitive as opposed to likely one-sided. A general rule is that people find competitive competitions more interesting.
Purdue then gets MD and Nebraska at home. Times are not announced. With a good record up to that point, the time of game gets moved back. IF it is moved back, that helps viewership of any game.
Purdue then gets Wisconsin and Iowa in WL. Does the earlier record suggest these are competitive and primetime games? If so, then viewership would be large.
IU opens against Illinois in primetime on a Friday night. That is good, but Purdue has an advantage because Purdue's game is the day before. Thursday is a better tv night than Friday for viewership of almost any show plus PSU is more highly regarded than Illinois at this point.
IU gets Idaho the next week in primetime and at home. This game should be a blowout. But Idaho has no name recognition and is a potential blowout. It is also up against USC-Stanford and ASU-Ok St as well and Michigan in a likely blowout. I do not see that helping viewership.
WKy at home is next. WKy is a team that a B1G team should beat but they tend to be severely underrated. It is a team that one is reluctant to play because you are expected to beat them but often do not. This game often hurts you more than helps you.
Then on to Cincy on the road; Cincy has name and they lost a lot from last year. At home, IU has a real shot but this isn't at home. IU could be 3-0 going into this game and with the Cincy name this could get viewers. What matters going forward is can IU win this game. If so, they would get a lot of publicity which would help the cause. The next week is at home vs Nebraska and in the evening. I do not get the Nebraska pre-season hype, but an undefeated IU team in the evening should get numbers.
I do not see IU beating Michigan, even in Bloomington. Evidently the B1G doesn't either as it is an early game. Out of Maryland at home and Rutgers on the road, I see one win.
Then comes PSU (H), OSU (A), MSU (A) and Purdue (H). I see 1-3 or 0-4 here; max is 2-2. My reasoning is PSU has a depth advantage and it is the time in the season where injuries pile up. Purdue has an advantage getting. PSU early. OSU is just better and at home. I expect MSU to back off from last year but they are at home. As for Purdue, it is a rivalry game and IU is at home. The problem is IU will have played 3 previous physical teams and may be beaten up. A lot of the viewership issues will be if IU can win a game that they are not favored to do so early. That would suggest 2019 and 2020 were not flashes in the pan but the program turning around.
But as I said earlier, injuries can throw all of the analysis out for either team. There are a lot of wild cards in the deck here; professional poker players never use wild cards because the ability to make good estimates of probability get thrown away. But good records get good numbers. Competitive games are more interesting than blowouts, even if you are on the winning side.
I think that the key to IU's viewership numbers will be determined by the WKy and Cincinnati games. 2-0 makes them interesting going forward; 0-2 is a disaster and 1-1 is meh. Those games set the tone for the B1G season.