Prabhas in Kapil Sharma show Revealed the meaning of Sahoo, He told it's a Sanskrit term for Jai Ho...
As per my Knowledge How Sahoo Replaced by Jai Ho in Modern Hindi..
Sahoo, साहो (Sanskrit)-----> Sadho, साधो* (Old,Shuddh Hindi)---->Jai Ho, जय हो (Modern Hindi).
*Sadho,साधो (Not to be confused with Sadho used for Sadhu in some Hindi Dialect)