Whether these decisions were his or not is an opinion, no one can definitively know at this point. However, what is known at this point is that it is highly unlikely. A few reasons.
First, Chiang rejected American officers leading Chinese troops. Second, his officers only obey Chiang personally. Example, during the battle of Shanghai, commander of the battle cannot order three German equipped artillery regiment without Chiang's personal written approval. This was later confirmed, as that man defected to PRC.
A possibility of a misunderstanding, or a misapprehension here.
Stilwell's role was not so much as a battlefield commander as one of a strategist, who wanted Chinese troops to be deployed only through him, and after he was persuaded, and who wanted all decisions relating to China, the Chinese establishment and Chinese troops to be routed through him.
This DOES NOT necessarily mean that he sought to exercise day-to-day command over the Chinese Nationalist troops; it meant that the British had to speak to the Chinese through him.
Third Stillwell was withdrawn, because he was not much of a yes man. Chiang worked well with Chennault, mostly because he had ideas similar to Chiang. The American perspective shares this view. Stilwell wanted command of Chiang's troops and Chiang would sooner die then let someone else do that, as proven when he was replaced as president during the civil war.
The disposal of Chinese troops, I can understand. Day-to-day operational command seems unlikely.
So almost all evidence would point to Chiang being the man that made the call. He had to be the one to give the order, because there is no way in hell Du would listen to Stilwell, if nothing else the fact he was made a war zone commander during the civil war showed as much.
Quite possible and not contradictory to the impression that the British had, not in the sense that they still had to deal with Stilwell, no matter who was taking orders from whom within the Chinese chain of command.
Now the reputation of the Nationalist troops is good in PRC, a lot of TV shows shows them as the key in battle. This is not a foreign concept in China. Maybe during the height of revolution this may have been misrepresented, today. No.
Please go back to the picture which I protested, and the mocking remarks addressed by a member. I protested that, and not the current value put to the Nationalist troops within China today. It is heartening to note that their contributions have been acknowledged and are known.
The evidence is convincing, especially in terms of the personalities involved. However, it is the context that counts, and this is where those theories about one objective truth existing break down.
SEAC never, or rarely heard from Chinese officers; all matters relating to the Chinese troops was rigidly channeled through Stilwell, who was hated by the British and the Chinese alike, for rather similar reasons. So whatever the internal workings, and the account given above may very well have been accurate, as far as the SEAC was concerned, all that happened within the Chinese chain of command was reported by Stilwell, and reported in possessive terms.
[An aside] While Claire Chennault was said to have been easier to handle, he was at an obvious disadvantage due to the nature of the campaigning having been so heavily terrestrial (yes, the irony of a naval admiral heading the entire organisation is also apparent, but then there was hope that at a later stage, after winning back Burma and Singapore, there would be amphibious operations and naval operations in the Dutch East Indies, as Indonesia was then known).