Bitcoin is a piece of code, it has no life essence and can kickstart anytime someone wants to boost it.  Even if it stopped for some time as long as there is someone or some group that is willing to support the network, Bitcoin will never cease to exist.  It can be hard for the government to totally shutdown the Bitcoin network but as the early reply said, Bitcoin is not a stand-alone application to run, it still needs a device, connection, and power to move the network in solving blocks.  Unless all is fully automated Bitcoin's existence is tied to human activity.

So instead of saying Bitcoin is immortal, I believe it is more appropriate to say that Bitcoin is quasi-immortal.