Based off prior experience with game jams I've done (GMTK 2019, GMTK 2020 and Yogscast Jingle Jam 2019), the number of rating does not matter as much when it comes to where you rank, what matters is your average rating score  in each category. The higher your average rating in a category, the more likely you will rank in the top 100 of that category. I do believe that the number of ratings you get does have a weighting that influences your score, which is known as your weighted score which is what is used to determine your ranking in each category when they are displayed in the results. For some reason however, the raw score and the weighted score for me in previous jams have been the same which means it might be broken.  The people who run itch.io may have changed how it works, and the same could be assumed for Blackthornprod since he runs the jam and can adjust some things (not really sure, I've never tried to run a game jam), so it may work completely different for this jam. Here's a link to how itch.io jams work for a more detailed understanding: https://itch.io/docs/creators/game-jams.

TLDR; your average rating score in each category is what determines your ranking, more so than the number of ratings you get

In the previous jams I have participated in, the Brackeys Game Jam 2020.1 and .2 as well as the Community Game Jam, the required ratings were 20, so I'd say it's the same here.