Its common knowledge that Japan attacked the Pearl Harbor in the hopes of crippling our navy to the point where we had no choice but to stay out of the war, are there any historians that believe that this attack caused their defeat because we might have never entered it otherwise?

This rests on a false premise: Yamamoto's reasoning for the Pearl Harbor attack was not to scare the US out of the war, but to buy time for Japan's forces to establish a defense perimeter formidable enough to destroy the inevitable American counterattack.

If I recall my history correctly, the mentality of the U.S. before that attack was very anti war, mainly as a reaction to WWI? I have read in other places however that the U.S. joining the war was inevitable due to our allies being under attack (by japan? by germany? both?), is this true?

Something like 51% of Americans supported anything, up to and including armed force, to stop Japanese actions in the Pacific (namely: China) before Pearl Harbor. And for all intents and purposes, the US was providing the logistics base for the entire Allied war effort before Pearl Harbor.

I talk a bit more about the Japanese rationale for attacking Pearl here.

Japan attacked Pearl Harbor on a big gamble that they could damage the U.S. Pacific Fleet to the point that they could consolidate their gains in Southeast Asia (they also attacked Hong Kong and Malaya almost simultaneously) before the U.S. arrived and then they could (with luck as an integral part of plan) fight their way to a settlement. Part of this plan rested on the idea that Roosevelt would focus on Germany first, and although the Japanese high command was quite aware of U.S. industrial capacity, they didn't think U.S. could wage two fronts so effectively.

To answer your question about whether Pearl Harbor caused their defeat, the short answer is yes. While war was likely, it was still preventable all the way up until Pearl Harbor. The U.S. made heavy demands on Japan to negotiate some sort of normalization of ties (to leave China and Manchuria, the latter of which the Japanese had invested billions in the last decade). This of course would've essentially reversed all the gains the empire had made and was a very hard pill to swallow, but it was possible.

It's also hard to know just how motivated Americans would have been to fight the Japanese if there had not been a direct attack like Pearl Harbor. If in fact the reasoning to enter the war had come from purely German deeds (or one incident specifically) then perhaps after Germany was defeated the American people would not have been as eager to keep on going with war with Japan especially given just how bloody it got. A settlement instead of total surrender could've been arranged by which Japan might've kept some of its empire. But that much is speculation. The point of the matter is that while war was more than likely, it was still avoidable and the attack on Pearl Harbor directly led to the total defeat of Japan.