How many universes "branch off" from a "quantum event", and in how many of them is the cat dead vs alive, and what about non-50/50 scenarios, and please answer so that a physics dummy can maybe kind of understand?

(Is it just 1 with the live cat and 1 with the dead one?)

How many ink blots are in this picture ?

For "many worlds", imagine that evolving in time, with fuzzy borders.

The Many Worlds Interpretation doesn't imply a countable number of worlds that suddenly branch, it's more like a fuzzy continuum; talking of branching worlds and timelines is just a high-level abstraction that makes things easier to discuss.

It rather seems to me an imprecise analogy which makes thinks harder to discuss. But I agree with the general sentiment.