What is the correct etiquette way to request quest to bring gifts to the 50th birthday party?:)

There IS no correct etiquette to ask for gifts.

Ever.

If guests ASK, you can answer, but it is NEVER correct etiquette to solicit for gifts.

You may register gifts at a store and note that on the invitation, just like a wedding or a baby shower, or you may ask that gifts be limited in value on the invitation. You may not make a gift the price of admission.

There is no correct way to ask for gifts. Those who want to give them will. Registries are for new babies (typically only a first baby for the parents) and first marriages. Anything beyond that is excessive and greedy.