No, it can't.
"Yes, let's go" would be "Ja, gehen wir" (imperative/"command" form with a different word order). Alternatively, you could use "lassen" (to let):"Ja, lass uns gehen", "Ja, lasst uns gehen" or "Ja, lassen Sie uns gehen".
What.. I typed: "Yes, we go." And this is still correct. Is this correct or not?
Because German isn't English :). It's perfectly possible to have a meaningful conversation without distinguishing between the simple and the progressive aspects. In fact, I believe that most languages don't have this distinction. Also, you can always add words such as "now" or "regularly" in German to avoid misunderstandings.
sie = she or they
"Wir sie gehen" would mean "We she go" or "We they go", i.e. it doesn't make sense.
If you wanted to write "Wir sind gehen" -- as I said above, Standard German doesn't distinguish between the simple (we go) and the progressive aspects (we are going). There is just one form for both:
We go. = Wir gehen.
We are going. = Wir gehen.