They have to know that the long-term return on this series is going to fantastic, it's beautiful and it's really good Start Trek -- with odd dashes of Seth McFarland esthetic. I think this will fly long enough for several collectable seasons just for the direct sales.
And this is where I share a resource.
TV By The Numbers. It's both informative and educational! Their
Renew/Cancel Index posts use the semi-public Nielsen Rating numbers sold to advertisers, media companies, and marketing agencies to try to guess at Nielsen's most elusive metric, the fabled "C30" ratings (viewership of ads per 30 minute segment of Television) that most of the broadcast networks in the United States use to either cancel or renew a show. The C30 ratings are an industry secret and are NEVER shared with the public, as that Nielsen product goes directly to TV Executives. The posts with the Cancellation Bear show programs that are considered "Dead Man Walking" to the advertisers with a small enough audience that the networks might pull the program from the air before it's over.
The educational part involves articles such as
The Third Season Rule, which explains that a show that is close to 100 episodes and middling ratings may get renewed for a fourth season anyway to try to package and sell the show to Syndication groups, or at the 88-episode mark for 'stripped' syndication conditional that another season is actively in production to make the 100 episodes before the deal is approved. (For 'limited series' type of shows that make less than 22 episodes available in a TV Season.) TV By The Numbers only tracks broadcast TV approvals: Cable works by a different metric which makes predictions impossible (On Cable, often critical response to a show may buck ratings and keep a show on the air. For broadcast TV, it rarely works.)
Concerning shows you're a fan of, this site should be helpful in tracking programs like The Orville's progress through the first year.