That depends on the number of streamers and viewers you're expecting.

As an example;
For a small 1 to 5 streamers with up to 20 viewers each, with transcoding enabled:

• Min 16GB RAM (Recommended 32GB+)
• At least 512GB of fast speed storage (SSD, NVME Recommended)
• 500 Mbps+ Network
• 8 Cores CPU (More is better)
• A decent CUDA compatible GPU (GTX 1080 or newer)

Note that these are just based on my experience, you might be able to get away with less than what I recommend to get started. You can also do without the GPU if you have a really good CPU (16+ cores) or if you disable transcoding. The software will run on a very small server, but performance may vary.

Transcoding is the most hardware dependent part.

The network speed requirements are easy to calculate.
Say your average stream is 2500Kbps with 20 viewers:
2500 * 20 = 50000Kbps = 50Mbps (1 stream with 20 viewers)
50Mbps * 10 = 500Mbps (10 streams)

(You always want to have more than what you "need" to avoid lag and buffering. Setting up a CDN like cloudflare is also recommended if you plan on scaling in any capacity)

I will be releasing some benchmarks soon to illustrate hardware requirements more accurately as part of the documentation.