Can powdered citric acid be used instead of baking soda?
No, those are absolutely not the same thing. They're completely different compounds: baking soda is sodium bicarbonate (NaHCO3), and citric acid is C6H8O7. And they're not even similar chemically: baking soda is a base, and citric acid is (surprise) an acid.

Also, to help out in the future, Google is actually really good for questions like this. If you search for baking soda or citric acid, then along with the usual web results you should get a knowledge panel with a brief description, chemical formula, various other simple facts, and a link to the Wikipedia page.