I’m afraid this is not a question easily answered. I would seriously think about talking to some CDN service (like Akamai). They usually have good solutions to streaming live TV to larger audiences, but that will come with a price.
Another client of mine was streaming a very low quality TV stream at 320kbps for approx. 200-500 (peak) viewers and even with a 90/10 cutoff (where the top 10 percent are not calculated) the streaming costs are astronomical!
To host the stream, you typically have a server located at the source of the TV stream, which feeds the RSTP straight into a preconfigured CDN server. Worst case is, if you happen to not be able to create that stream yourself, you would need to set one up, rent or purchase one. Just make sure that the feeding server has enough bandwidth to feed the signal once and protect the server from direct access (only the CDN being able to access the stream).
Seriously, talk to a CDN provider!