Both Ike and MacArthur almost certainly had to be aware of Rainbow 5 which had been adopted in 1939. Admiral Stark was the brain behind Rainbow 5 and Ike's recommendation to Marshall after the beginning of the war basically amounted to following the Rainbow 5 plan. It's an exaggeration to say that Ike "set wartime Pacific strategy", it had already been determined by Roosevelt's agreement with the British in 1940-41.

MacArthur had to be aware that of the decades-long debate within the US military/naval establishment about whether the Philippines would be "written off" or not. If he had any illusions about receiving resupply or reinforcement, it was because neither Roosevelt nor Marshall could bring themselves to tell Mac that there was nothing to send and no ships in which to send it. This painful duty was made even more difficult by the brief period between July and December, 1941, when the Roosevelt administration hoped that the hasty reinforcement of the Philippines might deter Japan.