Believe what you'd like.
Last time I checked, gravity was free.
It is. But it's unidirectional only.
The mutual attraction between masses won't cost you anything, but you still have to separate them to harness the energy. That isn't free. Just climb the stairwell of a 100 story building and ask if you feel tired. You've just converted food energy into gravitational potential.
Gravity is free - but you are proposing pumping water back uphill to its original level. That IS NOT. By simple laws of physics and because of mechanical inefficiencies, it will ALWAYS take more energy to pump the water back uphill than you will get out. RonF is right that you could use this as energy storage.
But it will NEVER work as a net producer of energy.
Yes and it equally pulls on water flowing downhill as well as water being pumped uphill.