Sherman's March to the Sea was a critical moment in the Civil War, one which had an impact in shaping its end. Sherman's strategy can be understood as a form of Total War, one which had the aim of destroying both the Confederacy's morale as well as its infrastructure and material resources. With this aim, Sherman marched deep into the Confederacy, destroying farms and plantations, barns, railroads, foodstuffs, and the like. This resulted in a great deal of devastation to the Southern economy (thus disrupting the Confederacy's ability to continue the war), as well as to the Confederacy's morale, particularly for the civilian population. Remember, to a large degree the Civil War was a test of endurance, with the Confederacy ultimately aiming to outlast and exhaust the Union's willingness to fight (even as most of the fighting in the Civil War was fought within Confederate territory). From this perspective, you might say that the March to the Sea showed the weakness of this approach to warfare through Sherman's strategic targeting of civilian resources.
With that in mind, the March to the Sea almost certainly had an impact in hastening the end of the war. It created large-scale economic and infrastructural damage deep within the Confederacy, and extended the cost of suffering directly to the civilian populace itself, thus damaging Southern morale.