Therefore he shall prosper in his way. He again reminds the Jews of the predictions, and claims for God this honor, that, by foretelling the event in due time, he has removed all doubt; and next he adds, that all that had been foretold shall be accomplished. Accordingly, in the repetition of the pronoun, It is I, it is I who have spoken, there is a double emphasis; first, tlmt none but the God of Israel hath spoken about future and hidden events, and secondly, that, because he is faithful and never deceives, all the events which he has foretold shall undoubtedly take place. Accordingly, in the last clause of the verse I consider the copulative v (vau) to mean therefore. Here Isaiah has two objects in view; first, that the captive Jews may expect deliverance, and secondly, that, after having been delivered, they may acknowledge God to be the author of so valuable a blessing, and may not imagine that it took place either by the assistance of men or by chance. Surely I have called him, I have conducted him. He declares that everything shall go prosperously with Cyrus, because Jehovah "hath called him;" not that he deserved so high a favor, or obtained it by his own industry or power, but because the Lord was pleased to employ the agency of Cyrus in delivering his people. As to his calling him beloved in the preceding verse, and now saying that he has been "called and conducted," I explained a little before that this cannot refer to the love of God, by which he adopts us to be his children and calls us to himself; for in this sense Cyrus was not "beloved" or "called." Though he was endowed with great virtues, yet he was stained by very great vices, ambition and the lust of power, avarice, cruelty, and other vices; and his lamentable end shewed what kind of person he was. The Prophet therefore means that God was favorable to Cyrus, so as to bestow upon him an external blessing, but not so as to adopt him, and to impart to him that grace which he bestows on the elect. We must consider the reason why he calls him by these names. It is because he makes use of the agency of Cyrus for delivering the Church, as we have already explained.

I, even I, have spoken - The word 'I' is repeated to give emphasis, and to furnish the utmost security that it should be certainly accomplished. It means, that Yahweh, and he alone, had declared this, and that it was entirely by his power that Cyrus had been raised up, and had been made prosperous.
Yea, I have called him - (See the note at Isaiah 41:2).
I have brought him - I have led him on his way in his conquests.
And he shall make his way prosperous - There is a change of person in this verse, from the first to the third, which is quite common in the writings of Isaiah.

I, even I, have spoken,.... What I will do, and what shall certainly come to pass; for not one word of the Lord ever fails; what he has spoken he will make good; what he has said to his Son in his council, and in covenant, or has delivered out by promise or prophecy, Numbers 23:19,
yea, I have called him; not Abraham, as the Targum; but Cyrus, whom he called by name, as well as called him to his work and office as a deliverer of his people, Isaiah 45:4 and so he called Christ also to his work and office, which he did not take to himself, but was called of God, Hebrews 5:4, I have brought him; from a far country, from Persia to Babylon; and who has also brought forth his servant, the branch, the Messiah, Zac 3:8,
and he shall make his way prosperous; or "his way shall be prosperous" (m); being made so by the Lord, who directed his way, and removed all difficulties and obstructions in it, Isaiah 45:1 and so the pleasure of the Lord has prospered in the hands of Christ, who has succeeded in the work of redemption and salvation he was called to, Isaiah 53:11, these are the words of God the Father, confirming what the Messiah said in the preceding, and who is introduced speaking in the next verse.
(m) "et prosperabitur via ejus", Pagninus, Montanus; "critique prospera via ejus", Vitringa.

brought--led him on his way.
he--change from the first to the third person [BARNES]. Jehovah shall make his (Cyrus') way prosperous.