matěj is nominativ. Shouldnt já be in accusative? (mě)
Arent the english rules for use of I/me the same as czech for já/mě?
Could you say: Já výdělává víc než Matěj
The traditionally correct English usage is "Matěj makes more than I (do/make)," and that is also accepted. However, I'd say the most common usage by far, at least in the US, is as shown above: "Matěj makes more than me."
And I'll add that the correct form is (já) vydělávám.