Rich Germans were super threatened by the ascension of labour movements (including socialism and communism). Hitler was basically the rich German's candidate of choice; he wasn't rich himself but the wealthy showered him with money to provide an effective counterpoint to populist socialism.
So how much you attribute the Holocaust to capitalism depends on your point of view. If you consider labour movements a totally necessary outcome of the extreme concentration of capital, and if you consider fascism as the natural reflex of the petit bourgeoisie when threatened by both capital concentration and organized labour at the same time, as Trotsky did, you probably believe capitalism is close to 100% at fault for the Holocaust - in the sense that, had there been an effective communist revolution, the Holocaust probably wouldn't have happened.
So how much you attribute the Holocaust to capitalism depends on your point of view. If you consider labour movements a totally necessary outcome of the extreme concentration of capital, and if you consider fascism as the natural reflex of the petit bourgeoisie when threatened by both capital concentration and organized labour at the same time, as Trotsky did, you probably believe capitalism is close to 100% at fault for the Holocaust - in the sense that, had there been an effective communist revolution, the Holocaust probably wouldn't have happened.