honestly i think they both feared the other but i think itachi feared him more because he believed tobi was madara which puts fear in everybody the fact is if itachi could have beat the 6 paths which i doubt he would have had to deal with all of the akatsuki members and honestly he would have been torn to pieces easily...he knew his place in the akatsuki
exactly the pains would have killed itachi, itachi never knew it was six of them he only seen deva path and didnt knw his abilities, no one could beat the pains without knowing what they can do as stated by the toad sage i dnt seen anything itachi could have done to beat the pains i honestly think he would have done as well as jiraiya did and he did okay because of that sound genjutsu and nagato's rinnegan dojutsu is = ms which is what itachi had so sight genjutsu was off limits and itachi doesnt have any sound genjutsu he would have been overwhelmed
first of all itachi would be fighting the pains not nagato he would be trying to seal 6 people which he doesnt have the time or the chakra for and that would take a long time and asura would absorb all of susano's chakra not just his shield and remember that shield blocks all elemental attacks well one of those paths can use mechanical weapons and how would he even get to deva path shinra tensei blocks all of that shit
also itachi barely beat a three tomoe sasuke while he was sick the pains would have tore sasuke as apart easily much easier than the fight with jiraiya
