The 43-year-old scored for Blackburn on their last Cup trip to Anfield, when they knocked the Reds out of the 1999-2000 competition with a 1-0 victory.
Rovers have already beaten Premier League sides Swansea and Stoke to reach Sunday's quarter-final.
"With confidence, you can achieve anything," former Wales international Blake told BBC Radio Lancashire.
Like the current side, Blackburn were playing in England's second-tier when they overcame Liverpool 15 years ago.
But Blake said the manner in which the Championship side defeated Stoke 4-1 in the fifth round made them a particularly dangerous proposition for Brendan Rodgers' Liverpool.
"The way they beat Stoke, it's not like they got away with it, they took them to task, put them to bed," said Blake, who also played for Cardiff, Sheffield United, Bolton, Wolverhampton Wanderers, Leicester and Leeds during a 15-year career.
"The manner in which they won that game, they should be flying high on confidence."
Blake recalled scoring his late winner against a Liverpool side that included a young Steven Gerrard as a "great memory".
He said: "I remember it being a real ding-dong game - it was a great occasion.
"Everyone had written us off, Blackburn as a club had been written off at the time, but we went to Anfield and it was a good game.
"I can't say we had it all over them at any point, but we held our own and quite late on I managed to pick up a ball from Per Frandsen and slot it with my right, first time."
Former Blackburn striker Nathan Blake says Rovers have the necessary belief to upset Liverpool again in the FA Cup.