The carburetor is probably varnished up. Before replacing I would try to clean the carburetor using SEAFOAM or equivalent (if there is an equivalent) to break down the varnish deposits.
If you squirt a tiny amount of starting fluid in the carb and the genny runs then varnish and gum is the most likely problem. BUT the generator not being run for a long time ay have gotten the electrical generating portion corroded which is another problem entirely.
But first see if you can get it running with a tiny bit of starting fluid. You may get lucky