Johnson was carried off on a stretcher in the second half of Saturday's 2-1 win at Blackburn with a knee injury. However, Gray said: "I think he is going to be okay."
Gray will also check on goalkeeper Paul Robinson, who played at Ewood Park despite missing the previous few days' training with a stomach bug, as well as Didier Domi who missed the game with a groin strain.
Everton will have Wayne Rooney back from suspension but Francis Jeffers will not feature again for Everton this season after a row with boss David Moyes, and will be sent back to Arsenal when his loan ends on June 1.
Moyes is also without defender Alan Stubbs (groin) while striker Kevin Campbell (illness) is doubtful but veteran defender David Weir is also back from a ban.
Leeds (from): Robinson, Kelly, Harte, Radebe, Camara, Duberry, Viduka, Pennant, McPhail, Smith, Seth Johnson, Matteo, Caldwell, Olembe, Lennon, Richardson, Domi, Kilgallon, Milner, Simon Johnson, Carson.
Everton (from): Martyn, Pistone, Hibbert, Yobo, Unsworth, Weir, Naysmith, McFadden, Gravesen, Carsley, Linderoth, Kilbane, Radzinski, Rooney, Watson, Campbell, Wright, Nyarko.
Gray will also check on goalkeeper Paul Robinson, who played at Ewood Park despite missing the previous few days' training with a stomach bug, as well as Didier Domi who missed the game with a groin strain.
Everton will have Wayne Rooney back from suspension but Francis Jeffers will not feature again for Everton this season after a row with boss David Moyes, and will be sent back to Arsenal when his loan ends on June 1.
Moyes is also without defender Alan Stubbs (groin) while striker Kevin Campbell (illness) is doubtful but veteran defender David Weir is also back from a ban.
Leeds (from): Robinson, Kelly, Harte, Radebe, Camara, Duberry, Viduka, Pennant, McPhail, Smith, Seth Johnson, Matteo, Caldwell, Olembe, Lennon, Richardson, Domi, Kilgallon, Milner, Simon Johnson, Carson.
Everton (from): Martyn, Pistone, Hibbert, Yobo, Unsworth, Weir, Naysmith, McFadden, Gravesen, Carsley, Linderoth, Kilbane, Radzinski, Rooney, Watson, Campbell, Wright, Nyarko.