Tade, who picked up a knock in the 2-0 win over Golden Arrows on December 22, has formed a strong partnership with Bongi Ndulu upfront, with the duo contributing 10 goals between them this season.
"Tade is hundred percent fit for the game," Johnson said ahead of the clash in Umlazi, Durban.
"We just have to wait and see if he will be starting."
Johnson expects a response from his men against the Lions of the North, who recently held title contenders Orlando Pirates to a 2-2 draw in Soweto.
"Our last game we didn't do well," Johnson said, referring to a 3-2 loss to high-flying Polokwane City last weekend.
"We have to make sure we change our mindset when it comes to such games."
He added: "We are facing a tough opponent in Highlands Park, who are coming from a very good performance against Orlando Pirates."
Usuthu handed Highlands their first home defeat of the campaign at Makhulong Stadium in November last year with a 2-0 scoreline, and Johnson expects the visitors to be eager to exact revenge.
"The King [Zwelithini Stadium] has been good to us," Johnson said.
"We know they will come with one thing in mind, to be the first team to beat us in Umlazi.
"I can tell you that we want to dominate at that stadium. It won't be easy for them."
AmaZulu are 13th on the Absa Premiership table with 14 points from 16 games - seven points behind ninth-placed Highlands.