View the original community article here
Last tested: May 13, 2020
Although you can manipulate both the colour gradient of map points and the size of the icon/circle based on a measure's value, they are both controlled by the same measure value.
Feature Request here to allow size to be controlled by one measure and colour gradient by a second measure
You can show multiple series in a map visualisation by pivoting. Those colours will show differently but the icons will be the same.