Sousa's future has been questioned after billionaire owner Flavio Briatore loaned top scorer Dexter Blackstock to Nottingham Forest without the manager's knowledge.
But Ephraim, after finding himself on the first-team periphery under John Gregory, Luigi de Canio and Iain Dowie, hopes Sousa will be allowed to build a dynasty at Rangers.
"I know for a fact that all the players are behind him and personally there's not one thing I wouldn't do for him," the 21-year-old told the Kilburn Times.
"He's like a father figure to me in football and I want to play under him, it's as simple as that. Hopefully that will be the case for a long time.
"He's taught me so much stuff it's unreal and all my gratitude goes to him."