How many different types of Eav Entity Types are available in Magento 2?

Magento supports Out-of-the-box Eav entity types for different Entity types.

You can check the list of Eav Entity Type from the eav_entity_type database table.

Out of the box Entity type code supported by Magento,

1. customer
2. customer_address
3. catalog_category
4. catalog_product
5. sales_order
6. invoice
7. creditmemo
8. shipment
9. rma_item (Magento Commerce)
10.gene_bluefoot_entity (Magento Commerce if Bluefoot is installed)

All of the above Eav Entity Types are available with Magento 2.