Some of the best GPU render farms support Octane render for Cinema 4D, including various options.

Render farms offer both CPU and GPU rendering capabilities and support popular 3D software and renderers, including 3ds Max, Maya, Blender, Houdini, and Octane renderer for Cinema 4D.
See also:
- Cannot Load 3ds Max Scene Directly From Dropbox Folder
- Package C4D Guide
- Powerful and Smart C4D render farm