Why is “Diva se na nas” is he looking at us, while “Diva se na to” is she looking at it?
In both cases it can be any gender. He, she or it. The Czech sentence does not specify the gender.
how do we know it is a he and not a she?
We don't, because the Czech sentence provides no indication of gender. "Is she looking at us?" would also be accepted. Please always read the existing discussion before posting.
Isn't "d" in "dívá" pronounced soft, as "ď " ?
Yes. The slow audio is correct.
Is "Does she see us" also correct?
no, that is "Vidí nás?"