' This is not exactly causative 'have'. I think you might say that it is a subclass of causative 'have'. Here 'have many people taking a closer look' means '(have) put many people in the position of taking a closer look' or '(have) influenced many people to take a closer look' or '(have) encouraged many people to take a closer look' or '(have) provided the impetus that led many people to take a closer look'.
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