Sodje, on loan from Reading, was an early doubt after injuring his shoulder on Saturday in the first leg at The Den, which Millwall won 1-0 thanks to Neil Harris' 71st-minute winner.
But Leeds manager Simon Grayson said: "It wasn't a dislocated shoulder like I thought afterwards. Sam felt something, he put it back in, and that was it.
"We had one or two bumps and bruises as you would expect, but I have everyone fit and available for the game."
Grayson added: "The boys were back in Sunday and were bright, bouncy, and thinking about Thursday. They've been good. We know what we've got to do and we are looking forward to it.
"These are the sort of games you want to play in. I wish I could play in it, but managing is the next best thing."