Increase vCPU number after the GravityZone import
After importing the GravityZone image in an ESXi, in "machine_name".vmx from the ESXi, virtualHW.version is set to 7 (virtualHW.version = "7"), the reason why it is not possible to use more than 8 vCPUs.
To be able to use more than 8 vCPUs, virtualHW.version must be set to 8: virtualHW.version = "8".
Copy the "machine_name".vmx from the "machine_name" folder within the ESXi data store.
Modify from virtualHW.version = "7" to virtualHW.version = "8".
Right-click on the machine from vSphere Client and Remove from Inventory.
Copy and replace the "machine_name".vmx within the ESXi data store.
Right-click on the "machine_name".vmx file from the data store and Add to Inventory.
From Edit Settings the number of vCPUs can now be raised to 32.