Ok, so, the /streams/:channel endpoint will return data if online, but not offline. So, if you want to get the active viewer count, yes, use /streams/:channel (i.e. /streams/illusionaryone). Now, if you want to get total views ever on the channel I would recommend the /channels/:channel (i.e. /channels/illusionaryone) endpoint, which will return the views data member off the primary object if the user is offline or online.
I hope that helps, if not, let me know!