Elgato Game Capture HD60 Pro has different maximum recording bitrates depending on software used.
4K Capture Utility: Up to 60Mbps at 1080p 60fps.
Game Capture HD (Hardware Encoder): Up to 60Mbps at 1080p 60fps.
Third party software (such as OBS studio) will receive uncompressed (YV12/4:2:0) video from HD60 Pro. As a result, there is no defined maximum bitrate in third party software.