Can you have multiple credit cards on one Apple ID

You can add another card(s), but the top card is primary and will be charged first. If there is a problem with the top card, an attempt will be made to charge the next card. You can not choose what card will be used to pay for a particular item.

You can have as many credit cards as you want.

although, your most popular card will be used first and when you are paying you can not choose which card you want to use. The only way it will not charge your top card at the time of a purchase is if for example; your top card have expired or is flagged. Then the system will use a different card but yes you can add as many cards.