When making Ghusl, does water have to reach the earring holes?

Yes, it is necessary that the water reaches the earring holes. However, it is not necessary to remove the earrings when taking a Fardh Ghusl. If there is certainty that water will easily enter the piercing with by merely pouring water over the area, then pouring water will suffice.

However, if there is uncertainty in regards to the water entering the piercing, then one is required to pay particular attention and ensure that water enters the piercing. This can be achieved by pouring water while rubbing simultaneously to get the water to enter the piercing. In both cases, as stated above, there is no need to remove the earrings.