There is no doubt that the US was going to enter the war before Pearl Harbor. Not only was American aid to the Allies massive (and increasing month by month), but the U.S. was already effectively at war with Germany - by mid-1941 American ships were escorting British convoys with orders to shoot German ships/aircraft on sight. There's a reason Hitler declared war on the US when he had no obligation to. Germany and the US were already in direct conflict.
While it did cross into the majority of Americans (68%) thinking we should join the Allies, it was due to the belief Germany wouldn't stop with Europe.
Interventionists believed the United States did have good reasons to get involved in World War II, particularly in Europe. The democracies of Western Europe, they argued, were a critical line of defense against Hitler’s fast-growing strength. If no European power remained as a check against Nazi Germany, the United States could become isolated in a world where the seas and a significant amount of territory and resources were controlled by a single powerful dictator. It would be, as President Franklin Delano Roosevelt put it, like “living at the point of a gun,” and the buffer provided by the Pacific and Atlantic would be useless.
Pearl Harbor settled the debate on if America would be left alone.