I'm making a renpy game with hand drawn art like this, and I've done a ton of research into the patreons of games like this, and 5k isn't anything special. Their patreon is 5 years old, although it doesn't seem like it started with this game.
Every single visual novel style game I can find that has custom art is making at
minimum 2k a month after 1 year of being released. And that's games with subpar art, little content, or just aren't very good to play. For a game with art as good as this, which has been running for almost exactly a year (Going by when this thread was made, and assuming for the sake of argument that ALL of that $4700 is from this game, and the 4 years of other games didn't contribute at all), 5k is pretty standard, if not on the low side.
For reference:
What a legend has been around for 11 months, and is making 6.5k a month. That's 30% more money for a slightly newer game.
Inquisitor Trainer is 9 months old and is making the same money as this game
Summertime Saga, while obviously much older at at least 3 years (their patreon got suspended around 3 years ago so all posts before then are gone, not sure how long it was running before that), is making $75k a month.
Driven Affairs released a demo
9 days ago and they're already making $772 a month
Lust Campus is at 3.2k after 6 months
Love & Sex Second Base 3 and a half years, $14.3k
Four Elements Trainer 4 and a half years, roughly $20-25k (just an estimate, they don't show their actual numbers)
So, while the paywalling isn't exactly breaking them, they could certainly be doing better. If we're gonna account for the 2 games with good art (almost equally good, but the artist has clearly improved over time) and the FULL 5 years, I'd be expecting them to make at least 3 times what they are now.