Optus did have a page called the student hub but I noticed this page no longer works and I have not seen any discussion on the student discount for some time. It still might pay to ask sales before making a purchase as they may have something going that is not advertised.
I've had a look through all of our current in-market offers and the student discount is no longer mentioned. In saying that, as @Yeldarb mentioned, definitely have a chat with sales. Last time I checked, the discount add-on was still available for agents to select.
Whether or it's not something they can offer, I can't make say for sure.