What does a typical passive site survey captures in determining the RF coverage of Wireless Access Point(s)?
Is there any relationship between the RF coverage with spatial streams or beamforming capability of an Access Point?
Passive survey is just capturing the unencrypted beacons and registering the signal strengths.
I didn't quite understand your second question. Could you rephrase it?
Beacons are always sent at lowest speed which means MCS0 1 stream 20 MHZ in most cases. So survey tools have no problems in detecting those and create a heatmap base on beacons. Multiple streams and wider bandwidths are are for data frames to from client, and they are not used in creating coverage maps.
Also there is no coverage maps that shows how far a client reaches. We have to wait for more sophisticated tools.