Blackburn manager Steve Kean faces a fight to avoid the sack after Championship club Cardiff claimed a 2-0 win over struggling Rovers in the League Cup quarter-finals on Tuesday.
Scotland striker Miller opened the scoring in the 19th minute with a low left-footed finish and Gerrard sealed the win by nodding home five minutes after the break after Blackburn keeper Mark Bunn had failed to deal with a corner.
At the other end David Goodwillie had his headed effort well saved by Cardiff keeper Tom Heaton and Scott Dann also nodded wide, but in truth Rovers -- who sit bottom of the Premier League -- were well beaten.
The visiting support made clear their dissatisfaction with repeated chants of "Kean out".
The evening had begun with both sets of fans uniting in a round of applause and a minute's silence in memory of Wales manager Gary Speed, with the home support regularly breaking into chants of "There's only one Gary Speed" throughout the contest.
Blackburn had most of the pressure in the early stages, but Morten Gamst Pedersen gifted the hosts the lead in the 19th minute.
Aron Gunnarsson seized on a poor pass by Pedersen to play Miller in to beat Bunn with a low left-footed finish.
It could have been 2-0 five minutes later as Miller jinked past Bunn, only for his shot to be blocked by Scott Dann with the home crowd baying for a handball against the former Birmingham man.
David Dunn's drive from distance was tipped round the post by Tom Heaton and a Dann header from the resulting corner was deflected over the bar as Blackburn rallied.
But it only proved a brief reprieve for the visitors as Cardiff doubled their lead through Gerrard.
Bunn came for a Peter Whittingham corner and got nowhere near it as Ben Turner headed back across goal for Gerrard to finish.
Heaton saved a strong Goodwillie header low down to his right before the Scotland striker was left furious when his claims that Cardiff left-back Andrew Taylor had fouled him as he raced through on goal were waved away by referee Martin Atkinson.
Source: AFP Global Edition