what qualities does gaston have which he uses to outsmart juleitte

Gaston uses his shrewdness and practical thinking to outsmart Juliette. He acts as a profit-oriented businessman, who is only motivated to make money, without bothering much about ethics, and succeeds in making a good amount of profit from a deal which involves zero investment. Thus, he can be claimed to be a better businessman than Juliette (though unethical).