Is the Ark of the Covenant needed in order for the Jews to use the Temple in the 70th week of Daniel?
There never was an ark in the 2nd Temple, and there won’t be one in the Millennial Temple. In Jeremiah 3:16-17 we’re told when Jerusalem is called the Throne of the Lord and all nations will gather there to honor the Lord, the ark will not be spoken of or remembered. It will not be missed and another one will not be made.
The only mention of the Ark in the New Testament that’s still in the future is the one in Rev. 11:19 and it’s in heaven, not on earth. Therefore, I think it’s safe to assume that the coming Temple could function without an ark.