Print the SVG to PDF from a browser, or run it through a vector toolchain. Either way, the output can stay fully vector, because SVG and PDF are both path-based formats. The catch is that most of the common ways people do this rasterize part or all of the document without any error telling you it happened.
The interesting question isn't "how do I convert SVG to PDF." It's "how do I convert it without turning vectors into a bitmap, and what specifically breaks when I do." That's what this post covers.
Same model, different container
SVG and PDF both describe drawings as paths, fills, strokes, and transforms. Converting one to the other is closer to re-encoding the same instructions than redrawing the artwork. Compare that to SVG to PNG, where you're committing to a pixel grid permanently. A correct SVG to PDF conversion keeps every path as a path down to the anchor points, not as sampled pixels.
Whether you actually get that depends on the conversion route and what the SVG contains.
