eazyBI does not support any configuration for the report and dashboard export to PDF. We have an idea for improvement on the backlog to support size customization for PDF export, but there is no estimate. I will post an update here if there are any changes.
Meanwhile, consider using page breaks and adjusting the relative widths of reports in the dashboard to control content. See the documentation on how to arrange repros in the dashboard: Create dashboards.
Best,
Zane / support@eazyBI.com