Kompany has been sidelined with a calf injury, and has featured in just nine of City’s 20 Premier League games but they have only conceded once while he has been on the field.
In contrast, they have kept only one clean sheet in the 11 games he has missed.
City are still unsure when the 29-year-old will return and Silva knows others will need to step up.
The Spaniard, who turned 30 last week, said: “Vinny is a key player for us and our captain. With or without him in the side we have to work hard to concede less, but it’s not just the defence that defends, it’s the whole team.
“It’s the same when we’re attacking — you need to have everyone helping out going forwards.
“So it’s down to us all to perform our defensive duties and it’s something we’ll be trying to do to help the cause.
“Any team will miss their captain when they’re out and we’re no exception but when you look all over the field there are lots of figures willing to step up to the plate when needed.
“We need to get a balance between conceding less but without lowering the total amount of goals we score or chances we create.”
City, who are third in the table but just three points behind leaders Arsenal, host Everton tonight in what could prove a pivotal night in the title race.
Arsenal face a difficult trip to Liverpool while second-placed Leicester travel to fourth-placed Tottenham.
Silva said: “It’s been a very exciting season and, above all, it’s very tight at the top.
“It’s going to be a close-run thing right through until the end of the season.
“Each game is tough, it always is, but somehow this year it’s even tougher and especially away from home.
“Every team is finding tough encounters on the road and I think you can lose at any moment when you least expect it.
“It’s about being competitive until the end of the season and being in the fight until the end.”
Manager Manuel Pellegrini recognises the importance of the fixture as he looks to manoeuvre his side into pole position but knows it is just one of many.
He said: “It’s important to try to reduce the gap as soon as we can with the two leaders but we are not going to win the title in January.
“I think it’s important to be solid and a consistent team from now until the end of the season.
“(There are) so many examples of teams that had the title in their hands in April, (but) they lose important points and after that they don’t win the title.
“So it’s important first to reduce the points that we are behind them and after that try to continue in all the competitions and try to be a solid and consistent team.”
Kompany is undergoing thorough analysis as City try to get to the bottom of his recurring calf problems and is likely to be out at least another month yet.
“I don’t think that he will be ready before a month,” Pellegrini said.
Despite Kompany’s woes, Pellegrini has no plans to sign cover during this month’s transfer window.
He said: “We have (Martin) Demichelis, we have (Nicolas) Otamendi, we have Bacary Sagna, who can play in a central defensive position, we have Cameron (Humphreys), who is a young player who featured in pre-season with the squad. (Eliaquim) Mangala will return soon.
“So, at this moment, we are not thinking about making a change.”
Romelu Lukaku is fit to lead the Everton line after recovering from an ankle problem.
Defender Ramiro Funes Mori is also available despite needing 10 stitches in a head wound at the weekend while Tim Howard will return in goal after making way for Joel Robles in the cups.
But midfielder Tom Cleverley (ankle) is rated 50/50 and full-back Seamus Coleman will be out for a couple more weeks with a calf injury.
“We feel very confident away from home, we’ve got a really good record,” said Toffees manager Roberto Martinez.
“I can see a really tight game and the familiarity between the two sides can only help to make it a more interesting encounter if anything.”
Martinez is hopeful of adding to his squad before the end of the January transfer window, and Ireland midfielders Aiden McGeady and Darron Gibson could be out the exit door.
Martinez said: “We’re going to work together with Aiden and his representative and we’re going to make the right call.
“There’s been three enquiries and it’s going to be over the next couple of weeks that we’re going to make the final decision.
“It would be a loan until the end of the season and (he and Gibson) would be returning and competing strongly in pre-season in view of the next campaign.”