And what percent of GTX 1080 users need their Blender to render faster?
Yeah. So, having more cores helps speed the render. The latest Blender does support Pascal. It's very fast. But your real limiting factor here is how much of the scene can you fit into the card's memory? Because if you exceed total memory capacity of the card, you'll be rendering on your system CPU.
A Titan X Pascal ships with 12GB RAM and a few more rendering cores. Compared to GTX 1080TI at 11GB, it's a marginal difference for a whopping $600 savings. So, if you're rendering 3D photorealistic in Cycles, your question is, will that 1GB difference really matter? Because if not, you'll want to buy a second GTX1080 for a bit more than one Titan X Pascal, and you'll blow a single card away in rendering times. Or buy four of them for less than 2.5x the price of two Titan Xs.
For 2D cartoons, you'll see some benefit in Blender using planes and onion skinning. But not with OpenToonz, which really doesn't have extensive GL acceleration yet. So choose hardware carefully to the projects you expect will pay the bills.
Who in their right mind does this? Pro animators, it's not just film but also advertising and motion design for web. Or architects, who often shoot proposed sites with a drone and then use a 3D model with motion tracking to composite them together for clients.
So, when you're paid by the project, each extra hour of rendertime really matters. And easily justifies a few extra thousand dollars in hardware.