I used this command when the servers A, B and C don't have a port other than 22
rsync -azv -e 'ssh -A -J UserServerB@AddressB' /file-in-ServerA UserServerC@AddresServerC:/path-ServerC
But if server B uses s port other than 22 to connect via ssh
rsync -azv -e 'ssh -A -J UserServerB@AddressB -p portB':PortB' /file-in-ServerA UserServerC@AddresServerC:/path-ServerC