If you copy a spell, Volcanic Torrent won't count the copy. However, if an effect instructs you to copy a card and then cast the copy, it will be counted by Volcanic Torrent.

The value of X is calculated as Volcanic Torrent resolves. It will include Volcanic Torrent, spells you cast in response to Volcanic Torrent, and spells you cast prior to casting Volcanic Torrent, even if those spells haven't resolved yet. For example, say the first spell you cast in a turn has cascade and that cascade ability causes you to cast Volcanic Torrent. Then Volcanic Torrent's cascade ability causes you to cast another spell. When Volcanic Torrent resolves, X will be 3.