About 50 rows should give you a bit more than 4 inches. That way you can measure row gauge on the middle 4 inches of the swatch.
Stitch gauge looks like it’s going to be more important for this hat so you may not need so many rows. As you knit the hat you may need more rows to reach a given measurement and more than likely the pattern will give you a measurement rather than a row number.
That’s indeed the pattern gauge. Add some sts and rows for the gauge swatch so you can measure over the middle 4 inches. That’ll give you a good idea of the gauge.
Since this is a small hat, the op might just start knitting the hat and see what gauge the hat measures, then adjust from there.