Maybe, but probably not
I can't find any proof of it, whether or for or against. That said, I think the evidence leans against it.
Points in favor: Hitler killed a lot of people and started a highly deadly war, which Khorne would appreciate. His armies did ravage entire nations. He was responsible for genocide during the second millenium. "Breed" sounds a bit like Nazi racial ideology. Warhammer doesn't have an aversion to Nazi references: the Empire of Mankind is full of them.
Points against: To begin with, it's hard to describe Hitler as a "mighty warlord." He wasn't known for his skill on the battlefield or wading into the fight. He was an administrator. Nor could he realistically be described as leading armies: he was only ever a Gefreiter, the second rank to which a soldier could be promoted, or a commander-in-chief far away from enemy lines. Although he arguably was not a strategic genius either, focusing more on his ideological goals, it's hard to imagine him wielding an axe and sword, tearing apart tanks.
Further, there are tons of other people who match the description better. Genghis Khan, for instance, was personally a great general, and also sacked nations and committed genocide. If we accept "around" M1/M2 as being rather loose, it could even be a warlord in the future from the perspective of the published content.
There's also no Nazi iconography with Doombreed's description. Further, his weapons don't exactly scream "Hitler": an axe, a staff, and a necklace? I'd expect him to use similar sorts of weapons to those he used in life, not switch from machine guns to axes.