Yes. Nasturtium and Pumpkin have a documented companion-planting benefit. University of Minnesota Extension reports research support for nasturtium and marigold reducing damage from squash bugs and cucumber beetles on squash and pumpkins.
This is a practical yes, not a magic guarantee. Keep the normal spacing for Nasturtium and Pumpkin, watch airflow and watering, and treat the companion note as one useful planning signal alongside sunlight, soil, and harvest timing.
Source basis: University of Minnesota Extension companion planting guide. The page does not add extra pest-control or yield claims beyond the sourced fact row.
Spacing tip: Leave vine crops room to run, or use a trellis so the companion is not shaded or smothered.