Smith's team were thrashed 4-1 by the Foxes at Villa Park in the Premier League on December 8 but a month on earned a 1-1 away draw in the the first leg of their Carabao Cup semi final.
Frederic Guilbert put Villa ahead at the King Power Stadium on Wednesday night and the visitors defended stoically in the second half to maintain that advantage.
"But since I've come in his confidence has grown an grown and we believe in him and believe in his talent and this season he has really come to the fore.
"He works so hard every day. He's either making a goal or scoring a goal now and he works so hard in his pressing game. He was a threat when he came on tonight and I'm delighted for him.
"It was a great finish. He's been so important for us. You see his confidence all the time whether he starts or comes into the game, and that's the beauty of him now – he is making an impact in games."