Leaders Manchester City will move 17 points clear of the Blues, who play Arsenal on Wednesday, if they win at home to Watford on Tuesday.
Cahill admits catching Manchester City is unlikely, but has high hopes the campaign can still end with silverware.
They face Arsenal in the League Cup semi-final this month, start their FA Cup campaign at Norwich on Saturday, while Barcelona await them in the last 16 of the Champions League.
He said: "Let's be realistic - City have got a massive points gap, but we just need to keep going.
"There are also other trophies to get so it can be a successful season. Let's look at the positives and go for what we can go for.
"City have been phenomenal this year. Our run over the last couple of months has been very good, but it's like what the other teams couldn't do with us last year - they couldn't do much about the fact we won 13 games in a row.
"I was looking at Tottenham last year and they kept getting wins, but we were winning all the time as well, so they were probably sat there thinking they couldn't do much more."