John Calvin, in his commentary on Isaiah 14, had this to say about the question of whether or not Isaiah 14 is speaking of Satan:
“The exposition of this passage, which some have given, as if it referred to Satan, has arisen from ignorance; for the context plainly shows that these statements must be understood in reference to the king of the Babylonians. But when passages of Scripture are taken up at random, and no attention is paid to the context, we need not wonder that mistakes of this kind frequently arise. Yet it was an instance of very gross ignorance, to imagine that Lucifer was the king of devils, and that the Prophet gave him this name. But as these inventions have no probability whatever, let us pass by them as useless fables.”
I still believe, though we should show restraint with the text and realize its limits, that it is possible that Isaiah 14 is referring indirectly to Satan, perhaps there condemning the King of Babylon’s actions by aligning those actions with Satan’s much greater epic fall from pride. The language of the passage, though poetry, is quite heightened, and it is possible that Paul in 1 Timothy 3:6 has this passage in mind.