On the contrary he had everything to lose. Backpedaling on his entire agenda, performing an about face would have been political suicide. Hitler stopping the war by himself in response to Gandhi could never have happened. Gandhi would have to have convinced not only Hitler but all of Hitler's henchmen. If they stopped the war, they would have all been finished politically. Their only rational end game was to keep marching forward.
If Hitler had approached his men saying you received an awakening letter from Gandhi which changed his outlook, he would have been regarded as crazy, probably stripped of his power.
> For, if a fair number of men and women be found in India who would be prepared without any ill will against the spoliators to lay down their lives rather than bend the knee to them ...
The Nazis were fanatics who were also willing to lay down their lives and did, including Hitler.