The most important word in the quotation might be "response," as it highlights Gatsby's obsession with how Daisy perceives him and his world.
Paraphrase: Gatsby constantly gazed at Daisy, and he seemed to appraise everything he owned based on how much it pleased her or caught her attention.
This tells us that Gatsby's entire identity and value system are centered around Daisy's approval and affection. It illustrates his intense desire for validation through her eyes, indicating that his sense of worth is deeply tied to her perception of him and his possessions. This obsession underscores his romantic idealism and the lengths he would go to win her love.