Héctor: Strictly speaking, the Spanish language does not have the sound /v/, so it is true that the verb “vivir” is commonly pronounced with the /b/ sound. Although language contact between English and Spanish, mainly within the hispanic community in the US, has blurred the lines a lot and it is also not so uncommon to hear this sound, especially in songs. Even me, as a native speaker, I mix them. Although normally, any ambiguities become clear in context.