Is there a way I can use smart contracts to stake nfts and back them with ada tokens. Similar to staking ada except also holding the nft in like a gallery or something.
No, this is because there is no way to know how much Ada the NFT is worth as far as the staking protocol is concerned.
Ada staking works with a 1 Ada = 1 Vote in deciding who mints the next block, so having 1 NFT = XXX Ada would be impossible to know without an Oracle of some kind.
"Staking NFT's backed by ADA tokens" is almost tautological. You can already think of your key pairs as non-fungible assets that are created and get "assigned" ADA (and other assets) when said ADA is deposited into the associated address.
However, the above is only true for main chain consensus. There is no reason that some other blockchain (or perhaps sidechain???) with a shelley-like consensus mechanism can't have different staking rules that include staking NFT's. In fact, I'd bet future developments in E-governance will result in some kind of proof-of-authority mechanism facilitated by NFTs.