Poyet's men head to Fulham on Saturday still on a high from their midweek Capital One Cup heroics against Manchester United, in which Johnson played a crucial role in coming off the bench to win the penalty which secured a famous 2-1 win.
Johnson's positive performance followed on from his match-winning display in the FA Cup third round win over Carlisle last Sunday and suggested he could be ready to rediscover the form which convinced the club to sign him for £10million from Manchester City in August 2012.
Poyet said: "When you have got a player like Adam who is on good form the chance that you will stay in the Premier League is massive.
"Adam has started the year fantastically and he made my day the other day so I am looking forward to seeing him stay on that level.
"I have seen him happier and more relaxed and really going for it. When we told him what we wanted him to do we didn't know if it was going to be possible, but he gave us all we wanted to see."
Johnson could have earned himself a place in the starting line-up for the trip to one of his side's chief relegation rivals which Poyet conceded could go some way towards determining the respective fates of the two sides this season.
The Uruguayan admits his chief priority has been to seek to instil a cup-winning mentality into his players' stop-start league campaign after a series of results - including knockout wins over Chelsea and United and a dismal home league loss to Aston Villa - that could hardly have been more contrasting.
Poyet added: "I will try to make them think we're playing in the Cup on Saturday. I'm looking for the difference if there is one. I think sometimes when you're playing for points you are in a situation where you sometimes unconsciously think a point away from home can be good enough.
"That way of forcing the game for the last 20 or 30 minutes because you want to win the game is different in the Cup, because you need to win. Can we create that mentality in the league? We'll try.
"We know that Fulham have been starting games fantastically so we will have to cope with that and impose our game.
"The Cup can go away quickly. Everyone thinks about it but then you play one more game and you can be out. So we need to concentrate on every game as it comes and now the most important, massive game is Fulham."
Poyet revealed this week he is on the verge of making Argentinian defender Santiago Vergini his second signing of the January transfer window following the rival of Marcos Alonso, who made his debut in midweek.
And more new faces are expected at the Stadium of Light this month with the manager admitting his impatience to get deals done in order to improve the quality of his squad for the crucial run of games ahead.
Poyet added: "We've got a few opportunities and we're working on them. I think it's important we add soon because we've got some very important games in the league in the next few weeks.
"The earlier you get them in, the better chance you have of adding quality to the team. I'm confident that we can do a few more deals."