No one knows for sure, and anything you might see on here is just a guess, although it could be an educated guess.
Another thing, you should probably clarify what you mean by "receive updates", as terms like that and "support" can mean different things depending on the context.
For example, receiving updates could mean able to download the newest iOS or it could mean being able to download an update that fixes a bug, or just a security update.
"Support" can also mean the same thing as "receiving updates", but could also include supporting HW, such as parts and repairs.
In your case, you are talking about the former, but if you go searching for an answer in other threads, it is important to understand the context of what the post is talking about.
Another thing, I don't think that Apple ever announces when an particular iPhone will stop getting updates (not counting new iOS support), it either happens or it doesn't.
Another thing to think about is that the chip used in the 13 Mini is still being used in devices that are currently sold. Apple often supports the chip, not necessarily the the year something is launched or is discontinued.
For example, the 5s (A7 chip), which was released 10 years ago got a security update earlier this year. The 5s was discontinued seven years prior to the security update. The 5c (A6 chip)was launched the same year as the 5s, but its last update was four years earlier than the 5s. The last 5c update was a minor GPS related update, and it was discontinued five years prior to this update.
So, there isn't exactly a set method used by Apple. With the A15 still being used in devices sold, and probably will be for a while, this could make the 13 Mini continue to get security updates for a long, long time.
MacWorld just had a decent article from a few days ago explaining how long to expect updates and support on iPhones.
Apple supports old iPhone iOSs for years, so even really old iPhones still get updates. But if it's iPhone XS parts you need you might not be so lucky.
www.macworld.com