If the TV has a headphone jack you can connect that to any input on the receiver except phono. The TV remote will control the volume. Start with it all the way down since it can overload the receiver.
If the TV only has optical out you will need an optical to analog converter.
Check the TV manual on how to use it. You may need to turn it on, the TV speakers off, and change the audio type to PCM stereo in the TV menu to get it working. The TV remote will not affect the volume.
Looking at the vintage of your Zenith, I suppose you want to hear TV sound thru that receiver, correct?
In that case - it depends what audio outputs your TV has. Mentioning the model will help us help you.
Whether your TV is smart or not, does not matter here.