In the short story "The Pedestrian" when the author says the television touched the faces of the people but never really touched them. What does he...

The tombs, ill-lit by television light, where the people sat like the dead, the gray or multicolored lights touching their faces, but never really touching them.

The touching part is fairly straightforward.  A television that is on in a dark room is the only luminous object in the room.  That means it produces light.  The light will travel away from the television at 300,000,000 m/s and hit any opaque object that is in the way....

The tombs, ill-lit by television light, where the people sat like the dead, the gray or multicolored lights touching their faces, but never really touching them.

The touching part is fairly straightforward.  A television that is on in a dark room is the only luminous object in the room.  That means it produces light.  The light will travel away from the television at 300,000,000 m/s and hit any opaque object that is in the way.  A person's face is an opaque object that is in the way, so the light will be touching the person.  

Light is not made of matter, so technically it can't touch anything.  Bradbury is a science guy, so he knows this, but that is not what he means.  What the quote is trying to convey is the fact that the things that the people are watching on television are ultimately empty and meaningless.  Most likely, the people are watching fictional stories about fictional people.  It's entertaining, but meaningless, because no matter what happens on the TV screen, it doesn't affect people and events in "real life."  Either that, or the people are in such a trance-like state that they are no longer "touched" or moved by anything that they see on television anymore.  They have become immune and desensitized.