The problem with Zuji is that you can't see the fare class that a fare books into unless you actually book the ticket.
You can contact Zuji support and ask, however you'll probably get a response like "You'll need to book the fare to find out". Give them a call though, and see if they can tell you...
Generally speaking though, for Business class on Cathay, just about all fares will book into points earning classes. It's Economy that has many, many classes that won't earn points, and cheap Cathay economy fares often book into those types of classes.
I suspect the fare will book into the I class (which is a points earning class) as are J, D and C. This covers just about all revenue business seats on their planes - but without being able to confirm it myself, I can't guarantee that will be the case.
The only thing to watch is that the flight is on Cathay metal (ie it isn't operated by anyone other than a oneWorld airline) as eg a flight CX999 which is operated by Malaysian Airlines won't earn points, but a flight CX998 on Cathay metal and a flight CX997 operated by Qantas will earn points/sc's.
The fare will either be a Zuji only special, or only sold in Singapore agent special. If you can find other online travel agencies based in Singapore (Priceline.com.sg doesn't offer it btw) then you might be able to find the same fare and the booking class.
Sorry I can't be more positive or informative, but hopefully that explains some of the issues around the fare.
BTW, welcome.