There does not appear to be an IP address assigned to the Pi and no clients are able to connect to this address for DNS.
*** [ DIAGNOSING ]: Networking
[✗] No IPv4 address(es) found on the eth0 interface.
[✗] No IPv6 address(es) found on the eth0 interface.
[i] Default IPv4 gateway: 192.168.1.1
* Pinging 192.168.1.1...
[✗] Gateway did not respond. (https://discourse.pi-hole.net/t/why-is-a-default-gateway-important-for-pi-hole/3546)
You have Pi-Hole configured to listen on this address, but that does not appear to be the IP address of the Pi: