Security guard detains a customer in a store and cuffs her for shoplifting can the guard be sued for this action?

That depends on the law of the place. Many countries allow for people who are not police, such as security guards, to make what are usually called "citizen's arrests". The rules for them vary, depending on where you are. If the guard didn't follow the law for citizen's arrests, then perhaps he or she could be sued for false imprisonment and/or assault.

In the US, the only state not allowing citizens arrest is North Carolina. In NC, you can only "detain". With detaining, you are not authorized to move the person (take them to the police station) against their consent. You can only hold them there. But it is definitely legal to do so if you witness them commit a felony, disrupt the peace, destroy or steal property (and there may be other instances).

Can the person sue? Sure, you can sue for anything nowadays.

Would the security guard be well within there rights, just as a private citizen, if they witnessed the person shoplift? Absolutely (providing they are in the US). If, however, the customer did not shoplift, that's a whole different story.