Yes, the word order is correct. The complement of time has to be at the end of the sentence. The complement of place has can be just after gens and before the phrase that qualifies it, or it can be part of the second clause: “Pourquoi est-ce qu’il y a tant de gens qui parlent français ici aujourd’hui?”. I can’t explain why these locations work and others don’t.
The word là should be ici instead. It’s happening here, not there.