How many characters were on the 1973 Pepsi glasses?

There isn't enough information to answer this question. There were many different kinds of Pepsi glasses in 1973, and they likely featured various characters depending on the design.

To help you get a better answer, you could be more specific by providing:

* The name of the specific 1973 Pepsi glass you are asking about.

* A description of the glass. For example, did it feature a cartoon character? A specific logo? A particular theme?

* A picture of the glass.

With more details, it would be easier to identify the glass and tell you which characters it featured.