The England striker had an immediate impact, creating a chance and hitting the post within minutes of coming on before scoring one goal and setting up Luis Suarez's controversial late equaliser.
"Daniel Sturridge made a hell of a difference, if he's in that type of form he's unstoppable and his performance gave the team a lift. The atmosphere was superb in the second half and on chances created we deserved at least a draw out of the game," Gerrard told the club's official website.
"I don't think the atmosphere was flat before the interval, the team was. Sometimes when we play at home it's down to the team to lift the crowd. We need to take the responsibility for being flat in the first half.
"In the second half, when they saw that we were prepared to give them a reaction, they got right behind us. I thought we were very unlucky not to win the game."
Sturridge has scored six goals in 12 appearances for Liverpool since joining the club in January.