Yes, ResearchGate preprints can be indexed in Google Scholar. Google Scholar automatically crawls and indexes content from various academic sources, including preprint repositories, conference papers, and journal articles. As long as the preprint is publicly accessible and formatted in a way that Google Scholar can recognize, it is likely to be indexed.

When it comes to citation indices, Google Scholar does include citations from preprints in its citation metrics for researchers. This means that if a preprint is indexed by Google Scholar and has been cited by other works, those citations will contribute to the researcher's citation count and related metrics (e.g., h-index) on Google Scholar. However, it is important to note that the citation counts and metrics can vary across different databases and indexing services, as they might have different coverage and inclusion criteria.