It is difficult to say for certain whether the United States would have entered World War II if not for the attack on Pearl Harbor. However, it is worth noting that the US had already been providing aid to Great Britain and other Allied powers prior to the attack. The Lend-Lease Act of 1941 allowed the US to provide military aid to countries fighting against the Axis powers, and President Franklin D. Roosevelt had publicly stated his support for the Allied cause.
It is also worth noting that tensions between the US and Japan had been escalating for some time prior to the attack on Pearl Harbor, with Japan's expansionist policies in Asia and the Pacific region viewed as a threat by many in the US government. The US had already imposed economic sanctions on Japan in an attempt to pressure them to change their policies.
So, while it is impossible to say for certain what would have happened if not for the attack on Pearl Harbor, it is likely that the US would have eventually become involved in World War II due to its support for the Allied powers and growing tensions with Japan.