The unofficial FAQ has a hint:
"But it's been a week / a month / a long time!"
Games in the review queue are prioritized by several criteria. The most important is having genuine traffic to the game page coming from outside itch.io. In other words: the best way to get your game reviewed sooner is to share the link around so people come and see it! If you wait for your game to be indexed it's just going to take even longer.
That said, if it takes a really long time, see the rules of this category for how you can get an answer more quickly.
Hope this helps.