The private 5G Network typically runs on carrier bands of the 5G spectrum that have been leased. A typical sized band is 1 Gb/s. Larger bands can be obtained from the cellular provider but do incur additional cost.
It is always safe to estimate that 80% of the bandwidth is available at any one time. The next decision is related to the intended usage. If it is solely for video offload, then the upload/download ratio would lean more towards upload.
As a rough guideline if 500 Mb/s is available for Video offload then theoretically 250 cameras can be uploaded concurrently. It then becomes a scheduling challenge to ensure that all buses do not come in to offload simultaneously in larger deployments.