Bruce, who could be offered £40,000 a week, is set to take charge after six seasons at Birmingham but Wigan will have to pay the club an unconfirmed £3m compensation.
Birmingham had dug their heels in demanding he stayed in temporary charge while they seek a replacement manager.
Bruce has told confidants he is ready for a new challenge and the prospect of trying to stave off Wigan's relegation threat excites him.
Further discussions are expected over the weekend and Bruce's appointment is likely to be confirmed on Monday, with the new manager paraded the following day when Wigan chairman Dave Whelan returns from holiday.
It's understood that Bruce has been promised money to spend on team strengthening when the transfer window reopens in January.