No you can't. Victor is a noun. I am the victor. Victorious is an adjective. I am victorious.

As Paul correctly states, one is a noun and the other an adjective. If you wanted to use 'victorious' in your sentence, you would need to add a noun after it - 'I am the victorious one". This might be appropriate if you were talking to someone and you wanted to emphasise that it was you who was victorious, rather than someone else.