England claimed a 4-1 win over Montenegro which means victory over Poland will secure a place in Brazil as Group H winners.
"The result will give us a huge lift and it's good for confidence going into the final game," Gerrard said.
"But the message is that the job's half done. Poland are a very good team. They're going to come and do us no favours, like Montenegro, try to make it really difficult for us.
"It's important that we perform to the same level as on Friday night."
England have secured a place in the play-offs at worst with the win, but know that will be their fate if they fail to beat Poland.
Ukraine's 1-0 defeat of Poland maintained their position one point behind Roy Hodgson's men, with just a clash against minnows San Marino to come.
The match in Kharkov finished prior to half-time at Wembley and England's players were aware of the result - and the added pressure - at the interval, when they were being held 0-0 by their visitors.
"We did (know the result) and it wasn't helpful," Gerrard said.
"The rumours were circulating which added that little bit more pressure.
"I said earlier in the week it was going to be a pressure situation. It's that critical stage in qualifying now and we took it on the chin, we accepted responsibility and we produced."
Much of England's success was a result of the attacking quartet chosen by Hodgson.
Wayne Rooney broke the deadlock, Andros Townsend flourished on his debut and scored and Daniel Sturridge netted a late penalty, while Danny Welbeck was a threat, even if he did not manage to score himself.
It was particularly satisfying after the scrutiny which England were subjected to following the goalless draw in Kiev in the previous recent qualifier.
"The team and the manager took a bit of criticism after Ukraine, but credit to the manager and the lads," Gerrard said.
"I thought the team selection was very bold - three forwards in the team and an out and out winger (Townsend). It paid off so credit to him for his bravery."
Gerrard knows England will require a repeat performance to reach Brazil, despite Poland being out of contention.
The Liverpool midfielder said: "They'll be coming to Wembley, they'll want to beat England, they'll want to be the team that stops us going to a World Cup.
"We won't be thinking they're going to take their foot off the gas."
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