Gunners boss Arsene Wenger could again utilise some of his fringe players when the npower Championship side come to Emirates Stadium for Saturday's fifth-round tie, with the likes of Jack Wilshere and captain Thomas Vermaelen both carrying injury concerns ahead of the Champions League showdown with Bayern Munich.
"A lot of players are back from international duty and need a bit of a break, so some may be rested for the FA Cup game, but that's just as important as we want to go far in that competition," Walcott said on the club's official website, arsenal.com.
The Gunners battled to a 1-0 win at Sunderland, where full-back Carl Jenkinson was sent off for two cautions and so will be suspended against Blackburn.
The victory edged Arsenal up into fifth to stay within striking distance of arch-rivals Tottenham, whom they face at White Hart Lane in a fortnight.
Walcott feels his team have the strength of character needed to come through the challenges ahead.
"We are very confident [of finishing in the top four]. We can battle through any sort of situation," he said.
"The teams around us are winning as well, but we have just got to make sure we look after ourselves and try to win as often as we can.
"We will see where we are at the end of the season, but we have got to show the belief we did at Sunderland.
"I felt there were a lot of winners in that dressing room and the boys were fantastic."