Unfortunately, a lot of what is said in Isaiah was added after Cyrus was long dead, leaving ample time in which to present god as a prophet of Jerusalem's rebuilding.
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The Book of Isaiah may not have been put into its present form until as late as 350 B.C., or well over three centuries after Isaiah's death." [And 180 years after the death of Cyrus]
Source: Asimov, Isaac.
Asimov's Guide to the Bible: Old testament. New York; Avon Books.1968,524
"In 536 B.C., [Cyrus] allowed the Jews to return to Jerusalem, but Cyrus died in 530 B.C.,"
source