Could the us have avoided joining World War 1?

Yes, they could have. It was true that Germany tried to get Mexico involved in the war on the Axis' side, but it is very improbable that Mexico - just recovering from a civil war - would have seriously considered starting a war with the US on behalf of Germany.

President Wilson - already sympathetic to the Allied's war effort - however managed to use Germany's efforts with Mexico as a way to successfully chance the isolationist attitude of Congress and the general public in the US.