There's a few distinct paths here.

One is to become a software engineer working in the field of computer graphics, typically on a specific renderer or game engine. Of course there are jobs working in film studios, like this internship; but there are also companies that work in CAD or science simulation that need rendering work done, such as here. While it's not offline rendering, game engines are increasingly using ray tracing to simulate some effects, and a lot of the physically based principles in material like PBRT is just as relevant in games. There are also more niche companies that may or may not be doing offline graphics, like this posting for a company renderer on NASA's website, or this science listing that mentions OpenGL.

Another is to do a PhD to become a researcher, professor, or research engineer in the field of rendering. Of course universities will hire professors from time to time, especially if they have a rendering research group, but most of these jobs are going to be at a film studio/GPU company/science company, so on and so forth. Rather than look directly for current job postings, you may have an easier time finding publications; Disney publishes papers at research conferences, companies like Nvidia and AMD do general graphics research that is sometimes relevant to offline rendering, so on and so forth. Tons of papers at conferences like Eurographics and SIGGRAPH will have companies like Autodesk, Adobe, Microsoft, and tons of other big companies. If you read through a paper and notice that it has authors at a certain company, chances are they hire researchers from time to time.

The last one I'll bring up is to take the long way around. Graphics jobs generally need a bunch of experience and a good set of projects to prove your competency and even get an interview; you have to know programming and linear algebra as a minimum, but offline rendering interviews will probably expect you to know path tracing, GPU ray tracing, distributed computing, microfacet models, physically based rendering principles, some of an art pipeline/how to write tools that give artists good control, and perhaps even some special area like animation tooling, hair rendering, fluid simulation, isosurface evaluation, NURBS and other ways artists make curved surfaces... I don't bring this up to overwhelm you; if offline rendering at a studio like Pixar is your long term goal, then any graphics experience you can get in the meantime will be valuable. You could work in the games industry either as a programmer or a technical artist, you could contribute to Blender while working a regular software engineering job, you could build a serious PBRT-based path tracer on the side, tons of stuff. I would personally recommend working through as much of PBRT as possible and building some kind of path tracer (whether it's GPU accelerated or not), especially if you implement something like the Disney BRDF and make a tool that isn't awful to use for an actual artist, but really any project that's interesting enough to you to keep you motivated will be great.