Yes you can see copepods if you have good eyes. They are about as big as the period when you type in a ten piont font.
A good place to look for them is in the corner of your tank, just above the sand. They are hard to see, I usually have to "zone out" on the tank before I see them.
You can create habitats for pods in two ways. One is to create a "refugium", and area outside the tank, with a little live rock and/or sand, and a cheap light, to give the pods a place to breed and grow. Ideally water would be pumped from the main tank to the refugium, and drain into the main tank, bringing pods with it. Or you can have it drain right into the sump, which is what I do, because I just don't have room for it anywhere else, the pods just have to make it through the return pump, not too much of a problem.
You can also create areas of refuge for pods in you tank. Some people call these "pod piles". Tank some rock rubble, and create little piles that your goby can't get into. When you feed, occasionally blow a little food into the piles, this will encourage the pods to live there and start breeding, when they venture out, the goby can make a snack out of them.
If you have ever bought live rock you should already have some.
-Laura