yes clearly if itachi HAD NO EYES sasuke could win, but in case you didn't know which evidently you don't EMS isn't any stronger than MS, the only difference is E(ternal)MS doesn't make you go blind hence the eternal. if there was some way that sasuke could have EMS without also having itachi's eyes then sasuke doesn't stand a chance.So what if he has got it becuase of Itachi? That doesnt change a thing that EMS Sasuke would be capable to defeat Itachi.