Is the collagen in evolence safe for use in humans? Is it true that the collagen in evolence comes from pigs? Why does the manufacturer use porcine collagen, and could my body reject this collagen after injection? .

It was. An excellent product, with only a rare risk of allergic reactions. It was discontinued by j&j several years ago. Today, we use juvederm, Restylane (dermal fillers) and the other ha gel fillers.
Yes . Yes it does come from pigs - and it has been discontinued by the manufacturer. There are many other good fillers available.