Why do you conclude that the "he" that confirms the covenant is the prince that shall come
"26 After the sixty-two ‘sevens,’ the Anointed One will be put to death and will have nothing. The people of the ruler who will come will destroy the city and the sanctuary. The end will come like a flood: War will continue until the end, and desolations have been decreed. 27 He will confirm a covenant with many for one ‘seven.’ In the middle of the ‘seven’ he will put an end to sacrifice and offering. And at the temple he will set up an abomination that causes desolation, until the end that is decreed is poured out on him."
Notice that in verse 26, the Anointed One (Christ crucified) is said to be cut of at the end of sixty-nine 'sevens." Then after that, "the ruler" of the people is mentioned. Therefore, in keeping with proper grammar, the one who makes the covenant in Dan.9:27 must refer back to the last person mentioned, which would not be the Anointed One who was cut off, but the ruler of the people who would come and destroy the city mentioned after the Anointed One.
Remember, the "he" in Daniel 9:27 is confirming an already existing covenant... he's not making a new covenant or peace treaty, he's confirming one that already exist... where is this covenant in scripture?
New International Version
He will confirm a covenant with many for one 'seven
New Living Translation
The ruler will make a treaty with the people for a period of one set of seven
English Standard Version
And he shall make a strong covenant with many for one week
New American Standard Bible
"And he will make a firm covenant with the many for one week
King James Bible
And he shall confirm the covenant with many for one week
Holman Christian Standard Bible
He will make a firm covenant with many for one week
American Standard Version
And he shall make a firm covenant with many for one week
I have listed several different translations of the same verse and as you can see, each of them demonstrates that he/the ruler, is the one who is making the covenant. No where in any of the translations does it show that he/the ruler is confirming an already existing covenant, but is in fact the one making the seven year covenant.