Not sure what exactly you mean. Zenphoto will read certain exif data when importing images (or refreshing meta data) like title, description and tags. Other exif values are just stored in the database. If these values are enabled for import on the options.
If meta data has any impact on SEO (you surely know that SEO can be complicated and has no real simple answers) depends if the theme used prints that data in public.
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If meta data has any impact on SEO (you surely know that SEO can be complicated and has no real simple answers) depends if the theme used prints that data in public.