Wes Hoolahan's 32nd-minute goal gave the Canaries a deserved lead, but Spurs winger Gareth Bale equalised after 80 minutes with a scintillating run from his own half which he finished off with a shot into the bottom corner.
Germany international Holtby, signed from Schalke, was introduced in the second period and delighted the Spurs boss.
Villas-Boas said: "He was good. The team improved so much in the second half that it obviously helped Lewis' performance.
"It was extremely good to see him out on the pitch. I think he had the right impact for such a short time."
Villas-Boas played down the prospect of a midfielder leaving White Hart Lane, even though Tom Huddlestone was not in the squad.
He said: "There was an interest from Fulham. I'm not sure if they're going to follow on that interest. He's a player we rate very highly."