Impact of the game:
What a win means for the Buckeyes:
According to the Worldwide leader's FPI (which I actually think is pretty good usually) this is, by far, Ohio State's toughest game. FPI gives the Buckeyes a slightly less than 50/50 chance to win this one, around 70% to win the @MSU and vsM games and better for all of the others. There is a decent chance that with a win here the Buckeyes will earn themselves a mulligan and be able to lose any one remaining game and still get to the B1GCG (the likeliest exceptions being Michigan and Michigan State but they both have other tough games remaining).
The win would hardly clinch the B1G-E but it would make Ohio State the obvious and strong favorite.
What a loss means for the Buckeyes:
Obviously, with a loss, the Buckeyes couldn't win a H2H tie with Penn State and, as I covered in my tiebreaker thread the Buckeyes would also be extraordinarily unlikely to win a 3-way tie with PSU/M (or MSU for that matter). That means that if the Buckeyes lose here they'll need help to get to Indianapolis. What they Buckeyes will need is for PSU to lose twice but that isn't completely unrealistic because the Nittany Lions still have to travel to Ann Arbor and they also host the Badgers, Spartans, and Hawkeyes. Additionally, the Nittany Lions have a ridiculous three-week stretch in late October / early November where they host Iowa, travel to Michigan, and host Wisconsin. Finally, just like 2016 there is the chance that an 11-1 tOSU could get into the playoff without going to the B1GCG but that seems a LOT less likely this year because Penn State was perfect OOC.
The loss wouldn't eliminate the Buckeyes from the B1GCG/CFP races but it would eliminate their margin for error.
What a win means for the Nittany Lions:
It would mean that PSU won a tough home game but they would still need to do that three more times (MSU, Iowa, UW) plus deal with a road trip to Michigan that happens to be tucked in between hosting the best two teams in the B1G-W. I'm not saying that a win wouldn't help Penn State, it certainly would. What I am pointing out is that a win here does not put Penn State in quite as commanding of a position as one might be led to believe.
The win would help Penn State but there would still be plenty of work left to do.
What a loss means for the Nittany Lions:
Penn State would likely win a 3-way tie with tOSU and M and in theory that could still happen even if PSU loses tomorrow but it seems pretty unlikely to me that the road team would end up winning all three of tOSU@PSU, PSU@M, and M@tOSU. Aside from that possibility, the Nittany Lions would need Ohio State to lose twice. That is far from impossible but it requires some things that just don't seem very likely. It would require MSU and M to be good enough to beat the tOSU team that beat PSU (M on the road) while those teams would still have to be bad enough to lose in Happy Valley (MSU) and at home (M) to the Nittany Lions. Stranger things have happened but this combination of results is not very likely.
The loss would put PSU in the odd position of hoping that M and MSU are really good (when they play tOSU) but not so good (when they play PSU).