Norwich are just three points clear of the relegation zone, having won one of their last six matches.
However, Johnson is confident the club can pull away from trouble and takes heart from a spirited display against Manchester United on Saturday, which saw Chris Hughton's side spurn several chances before going down 1-0.
Ahead of Wednesday's trip to Palace, Johnson said: "We've got a lot of positives to take out of the (United) game, although we lost it.
"We haven't talked about the game that much, but we're going into Wednesday confident we can repeat the performance and pick up the points.
"I think we were unlucky not to score. On another day we may have scored three or four but we didn't and it cost us.
"We're (still) confident and hopefully we'll put away some of our chances (against Palace).
"Everyone says they're massive games but for us it's a long season, and we're halfway there now and we're not in the bottom three.
"Although they (Palace) are going to be fighting for their lives to get the points, we'll be doing the same.
"We want to get as many points as we can this year and we're confident we can pick up three points."
