Jones lost his five-year-old son, Luca, to leukaemia last November.
He made his first Barclays Premier League appearance for Liverpool at Blackburn on Tuesday when he came on as a substitute after Pepe Reina's understudy Alexander Doni had been sent off. His unexpected role came six days after his partner, Dani Lawrence, gave birth to a boy named Nico.
"When Brad looked up to the sky (after saving the penalty) it was a special moment for football," said Cahill. "To have two Aussies in an FA Cup semi-final is massive. I sent him a text but his mind is a whirlwind of emotions at the minute."