I'm not comfortable answering the totality of your question as there were many factors from transportation to progressive ideals, but one thing I do want to point out is that the burning of Atlanta had a minor impact on the growth of the city overall. In fact the Civil War generally may have been one of the most important influences on the growth of the city- during the reconstruction years between 1860 and 1870, the city doubled in population. This resulted in part because many freed slaves relocated to urban areas seeking work- by 1870 the city was nearly half black. See generally: Atlanta and its Builders, A Comprehensive History of the Gate City of the South by Thomas H. Martin.