No, an armed Jewish populace probably would not have stopped the Holocaust from happening on some scale.
But armed Jews absolutely would have resulted in more dead Nazis.
And that is a good thing.
Or, as Aleksandr Solzhenitsyn said regarding a different murderous atrocity in a different socialist country:
And how we burned in the camps later, thinking: What would things have been like if every Security operative, when he went out at night to make an arrest, had been uncertain whether he would return alive and had to say good-bye to his family? Or if, during periods of mass arrests, as for example in Leningrad, when they arrested a quarter of the entire city, people had not simply sat there in their lairs, paling with terror at every bang of the downstairs door and at every step on the staircase, but had understood they had nothing left to lose and had boldly set up in the downstairs hall an ambush of half a dozen people with axes, hammers, pokers, or whatever else was at hand?… The Organs would very quickly have suffered a shortage of officers and transport and, notwithstanding all of Stalin’s thirst, the cursed machine would have ground to a halt!