There are several factors that you must consider before you can conclude on how many websites can you host on one single dedicated server. There is no fixed limit as in a
dedicated server, the entire space is yours. It will entirely depend on the type of website. You can easily host several low-traffic websites on your server so long as the resources are not taxed.
If your websites are popular and pull high-traffic constantly, you will require more space, bandwidth, memory etc. to ensure your website does not slow down or crash due to load pressure.
Dynamic websites with video or music content, huge databases,
email services and similar large files will need more bandwidth to ensure there is no latency while uploading or downloading the files.
Another important consideration is the hardware configuration on the server. How large the server hard drive is, the CPU speed, the network connection speed etc. You must also consider that the operating system will consume some of the resources. It is important that your website should be responsive and run comfortably across all devices even at peak times. Speed and up-time are two crucial requirements. Hosting many high traffic websites on one server is as risky as a
shared server is.