Having a lot of subs does not guarantee stable finances, and low sub counts don't hinder it. If you are good at hunting down commissions, you can do art full time even if you have a small amount of subs. If you have a lot of subs but don't know how to keep them engaged or you dont have products for sale that are attractive enough to purchase, then those subs are useless from a financial standpoint (of course they aren't worthless in general; having eyes on your work is incredibly valuable if that is your intent).
So noone can give you a specific subcount and say "at this subcount you will earn that amount", because it will differ vastly even among people of similar subscriber amounts. Some people in the webcomic industry earn $6-10k a month on patreon alone monthly, others of equal subscriber amount may struggle to earn anything at all because they update too rarely or don't utilize monetization tools properly.
I do webcomics full time. I have multiple income sources, and the biggest advice i can give you is to do just that. Don't put all of your eggs in one basket, because sometimes unexpected things happen and when it does you will need other income sources to keep you afloat until the situation is figured out.
I have 60k+ subs on tapas alone as of right now and my total income average this year that passed has been $1.5k monthly. Next year looks like it will take off on $2k monthly and hopefully slowly rise from there.
There are artists with fewer subs than me who make more money.
If you wanna make it in webcomics, though, do keep monetization in mind but don't make it your main goal. If you think you have to compromise your happiness, health and artistic goals at any point in order to make it then you are 1. Headed for a toxic mindset that isn't even necessary in this business, 2. Doing things the wrong way, and 3. It's just not worth it, especially not with money as your sole motivation. You will undoubtedly end up unhappy if you do this.
Work primarily with things you like but dont be afraid to go out of your comfort zone at times if you have to in order to pay the bills. But basically, if you go so far from what you want to make that you find yourself absolutely hating what you create, then you may as well skip it and get a job in fast food instead. Respect yourself, respect your wishes, respect your own health, nurture your dreams.
