Does organic decay release the same CO2 as burning?
I can't quantify the answer, but intuitively, nearly all of a burning tree's carbon is converted to $\small\mathsf{CO_2}$ - assuming the fire is hot enough. You are correct in assuming that termites and bacteria convert some of the carbon to other organic species, as do fungi, yeasts, moulds, and slow weathering. In addition, some of the rotting tree's carbon is converted to soluble inorganic ions, humic, fulvic and tannic acids. So no, organic decay would not yield the same $\small\mathsf{CO_2}$ as burning.

This would make an interesting school or 1st-year uni science experiment. Burn some wood in a sealed environment, measure the $\small\mathsf{CO_2}$ evolved, then repeat the experiment with wood in a wet organic-rich isolated biome, and compare the results. I suspect it would make for an interesting paper with potential climate change policy implications.