On a FJ discount economy ticketed fare, is a business class upgrade paid for in cash at checkin eligible for business class points and status as a Qantas FF?

On a FJ discount economy ticketed fare, is a business class upgrade paid for in cash at checkin eligible for business class points and status as a Qantas FF?

I think so, Have not done an upgrade at checkin but instead over the phone about a week before and got all the QF points and status credits

So in other words, your case differs completely to that posed above?

No.

I have upgraded from J to A at check-in; before and you only points and status credits on the original fare you purchased. 

I have upgraded from J to A at check- before. You are only eliglble for status credits and ff points on the fare that you originally purchased.