Based on what I read it is possible to forward logs from ArcSight to McAfee SIEM using CEF. However, I think this is limited to the upcoming logs only.
Is there a way or does McAfee SIEM support the ingestion of the old events generated by the connectors/data sources of ArcSight?
Usually not. Importing old data into an SIEM is problematic due to aggregation. You could send them to the ELM and they would still be searchable though.