Although the names of indigenous territories can be found in search in both Google Maps and Google Earth, the outlines only show in Google Maps. Even the web version of Google Earth, which largely shares the same database as Google Maps, does not show the outlines. Another issue is that even in Google Maps, there is no way to view all the outlines at once. It would be nice if Google were to add them to Google Earth either as second level admin regions, or a layer on their own.
When looking at Brazil in Google Earth, it is immediately apparent that some areas are not being cleared for cultivation. These are a mix of indigenous territories and protected regions (nature preserves of various kinds).
The indigenous territories are not completely free of visible human activity. The indigenous territory of Kayapó, for example includes a town, a road to the town, some signs of clearing presumably for cultivation and an area that appears to be surface gold mining.