Papers in prestigious journals matter, but the location of a citation does not really matter. As long as the source is included in whatever you're using to count citations (usually Google Scholar, Scopus, or Web of Science), a citation in Nature is no more valuable than one in PLOS ONE.
The only wrinkle to this is that citations in more popular venues are more likely to be seen and re-cited.
The only wrinkle to this is that citations in more popular venues are more likely to be seen and re-cited.