being Chuunin, and being of Chuunin level are different things. Genma told Sasuke he was 'of Chuunin level' indicating he was stronger and more tactical than the average Genin, which meant that Sasuke has a high chance of being promoted to Chuunin.
I'm not really sure if the kages are very important in the decision-making process, seeing as only one (kazekage) came to watch it... and both 'died'