The Robins now sit bottom of the Championship following this afternoon's 5-0 defeat away at Blackpool.
After the match at Bloomfield Road, Millen vowed to "fight on" as the club's manager, although he has admitted that his future is "out of my hands".
"We're bottom of the league, but I will continue all I can to prepare the players. My position is out of my hands, and it's not my decision, but I will continue to fight on. To lose 5-0 isn't acceptable," said Millen.
"I have been trying to get players in for a long time. I have had confidence in these lads for the last 10 games, but we're just not producing at the moment.
"We're getting a lot of criticism at the moment, and I am taking the majority of that, which is quite right, but the players have to stand up and be counted now."
City have not won any of their opening ten league fixtures.