Mauricio Pochettino's side have won their last nine top-flight matches in a row, but remain four points behind the leaders with only four matches remaining.
Kane, who scored the second in Spurs' 2-0 derby win over Arsenal last weekend, has hit 21 goals in 26 league appearances this term despite missing two separate spells with ankle injuries.
Spurs drew three matches in a row during Kane's first stint out in October and Bilic believes that run could have been the key factor behind Chelsea's advantage at the summit.
"I have nothing but praise for them [Tottenham]. When I watch them I wonder how Chelsea made that gap, but they had two periods without Harry Kane," said Bilic, whose side host Spurs on Friday.
"Spurs are in form, but they've been in form for two months. We are positive, four unbeaten and three clean sheets in four games.
"Yes, they are electric, with confidence, pace, passing and changing positions and everything, but our form also improved.
"Spurs are very versatile. Sometimes you know where the ball is going, but you can't stop it because of the quality."
Bilic's position at the club has come under scrutiny, but the former Besiktas boss insists he will not discuss his future or the transfer market in public until the end of the season.
"It's not the time to talk about my situation. It's the time to talk about the club. I'm very calm and focused on the game," he said.
"It's not the time to talk about transfers. We are talking about targets with the staff and the board, but not in public."