The whole concept seems eerily similar... a young child, groomed to be the main hope to win a war, with no adult support, and deceived about the main point of the struggle. This seems to go well beyond merely common tropes.
A young kid growing up in an oppressive family situation suddenly learns that he is one of a special class of children with special abilities, who are to be educated in a remote training facility where student life is dominated by an intense game played by teams flying in midair, at which this kid turns out to be exceptionally talented and a natural leader. He trains other kids in unauthorized extra sessions, which enrages his enemies, who attack him with the intention of killing him; but he is protected by his loyal, brilliant friends and gains strength from the love of some of his family members. He is given special guidance by an older man of legendary accomplishments who previously kept the enemy at bay. He goes on to become the crucial figure in a struggle against an unseen enemy who threatens the whole world. (Uncle Orson Reviews Everything, April 20, 2008 "Rowling, Lexicon, and Oz". Please note that - to be clear - Card himself was NOT asking JKR to acknowledge the influence, the topic of the piece was Rowling's lawsuits about Lexicon and he merely used this similarity as an argument that Rowling wasn't in the right about Lexicon)
Harry himself comments on the key similarity of letting him mature and struggle independently, on his own:
'No, it isn't,' said Harry thoughtfully. 'He's a funny man, Dumbledore. I think he sort of wanted to give me a chance. I think he knows more or less everything that goes on here, you know. I reckon he had a pretty good idea we were going to try, and instead of stopping us, he just taught us enough to help. I don't think it was an accident he let me find out how the Mirror worked. It's almost like he thought I had the right to face Voldemort if I could...' (P.S.)
Did JKR ever comment on whether she was in any way influenced by Orson Scott Card's "Ender's Game"?