By default, WordPress doesn’t allow you to upload SVGs because SVG has intrinsic security issues. That’s why theme does not support svg format.
If you do need to SVG upload support, you can install SVG support plugin. To allow to use SVG in theme options, you should redefine
presscore_get_logo_image function in your child theme, like this https://gist.github.com/bigdigital/59ada0c2a993af95eefd7dad156006cc
Then, add following CSS rule into Dashboard – Theme Options – Advanced – Custom CSS: