Here's a blog post about the V8 for those who aren't familiar.
https://rufautomobiles.com/ruf-v8/
I believe the V8 is on the backburner, it's not completely gone. I saw both the 997 and 991 prototypes when I was in Pfaffenhausen in Feb. The motor wasn't in the car.
I believe the costs came may have been a factor. But it may come back around again one day. You never know what RUF has up it's sleeve.
Remember, the goal for this engine was eventual twin-turbocharging for a CTR3 variant.