Southgate is under growing pressure after failing to win any of his last five games - the team's worst winless run since 2014.
England were relegated from their Nations League group following their recent 1-0 defeat to Italy, meaning Monday's game with Germany will be nothing more than a World Cup warm-up fixture.
"I am not foolish," said the England boss. "My sole focus at the moment is to get the team right for (Monday) night.
"We're focused on a good performance, a good result, then you're looking towards the World Cup. And I know ultimately I will be judged on what happens at that World Cup.
"Contracts are irrelevant in football because managers can have three, four, five-year contracts and if results aren't good enough then you accept that's time to part ways.
"Why would I be any different? I'm not arrogant enough to think that having a contract should protect me in any way from results."
Southgate later added: "Of course we understand how the mood changes with the results, and it has changed.
"I am realistic about that. I'll be judged on what's delivered in Qatar and I am perfectly happy to be judged in that way.
"History is history. You're judged on the next match and you're judged on the next tournament."