The former Scotland striker has spent two spells at the Ibrox club - he was there between 200 and 2001 and again from 2008 to 2011.
The 34-year-old trained at Murray Park when he returned to Scotland during the close season in North America.
And he is believed to be so keen to help Ally McCoist's side return to the top flight he has agreed to a massive cut in wages.
If the ex-Hibs, Wolves, Derby County and Cardiff City hit man puts pen to paper at the Gers he will be earning less than Seb Faure and Arnold Peralta.
McCoist has revealed that his player budget will be virtually the same in the SPFL Championship as it was in League One.
He is set to release out-of-contract players in the coming days in order to free up cash to bring in Bosman transfers like Miller.
Announcing that he had agreed to leave Vancouver last night, Miller said: "The club wanted to go in one direction, I wanted to go in another direction."