I suggest you pick up a copy of my book on Daniel, Daniel, Prophet to the Nations. It is available at www.ipibooks.com In this book, I go into a good amount of detail on the date of authorship of Daniel. Let me give a very brief rundown:
We cannot be absolutely sure when the final composition of Daniel was produced. Nor can we be absolutely certain why part of it is in Hebrew and part in Aramaic. We have to live with some uncertainty. We have to settle for asking what is the most likely scenario, not when exactly was it put in its final form. Clearly, someone did some editing to the material produced by Daniel. Daniel did not write the entire book himself. He is referred to in the third person. There is other evidence of editing of what came from Daniel. My conclusion from all the evidence is that both the Hebrew and Aramaic was put in its final form, possibly (but not likely) in the late sixth century, but more likely sometime in the fifth century BC, and possibly as late as the fourth century BC, based on the Greek words (only musical instruments, showing early influence) and the Aramaic style (the majority agree that it is of the Eastern type, most likely the fifth century, but plus or minus one century).
There is plenty of evidence of Daniel having been written well before the reign of Antiochus Epiphanes, and that is the key point. I would say that the evidence is conclusive that it was written certainly before 250 BC. People try to claim that the prophecies of the terror of Antiochus are so accurate because they were written after the fact. My conclusion (read my book) is that this is the result of presuppositional thinking, not the evidence. Here is the kicker: Sure, there is fantastically precise prophecy in Daniel 8 and 11 about Antiochus Epiphanes, but there is also fantastically precise prophecy about Domitian in Daniel 7 and about the coming of the Messiah to Jerusalem in Daniel 9 and the defeat of Antony and Cleopatra in Daniel 11 as well. Daniel 2 has prophecies that take us through the end of the Roman empire. It is this evidence that utterly defeats the presuppositionally-based claim that Daniel was written around 150 BC. Then there are the fragments of Daniel in the Dead Sea Scrolls, and the, admittedly indirect evidence that Daniel formed part of the Septuagint translation as early as the late third century BC. Besides, how could the Jewish teachers of the Law be duped into including a faked prophecy into their canon within a generation of its supposed authorship (as proved by the date of the Daniel fragments in the DSS)? This strains all credulity. No, Daniel is not a faked, deceitful prophecy.
As for Persian words in the Hebrew and Aramaic sections, Persian and Aramaic culture were overlapped in Mesopotamia for hundreds of years. I am more knowledgeable about the Greek, Hebrew and Aramaic in Daniel than the Persian loan-words, to be honest, but common sense says that because the Persian empire used Persian and Aramaic almost interchangeably, there would be more Persian words in the Aramaic section, no matter the date. It makes sense that there would be a good deal of overlap between Hebrew and Aramaic, but little Persian use in Hebrew, no matter the date. Bottom line, the Persian words do not imply Maccabean timing for the Hebrew of Daniel.
All this taken together proves beyond any reasonable doubt that Daniel was written well before the events of the persecution under Antiochus Epiphanes. That being true, then Daniel is certainly contains miraculously inspired prophecy. With that, the case for inspiration is settled, which means that, whether it was completed in the 400s or even possibly as late as the 300s is not an essential question, as the Book of Daniel is inspired by God.