I'm using wmts with geoserver by getting the capabilities like this:
By doing it this way, Arcgis is using the REST interface to get tiles. Is there any way to use the KVP interface?
You are correct. ArcGIS Runtime will always default to RESTful to get tiles from the server. This is the expected behavior for faster performance purposes. However, if the server does not provide a way to use REST to get tiles then ArcGIS Runtime will go take the KVP route.
Additionally, would you like to share the reason you want to use KVP for requesting tiles? Maybe I can help you with a workaround.