Gabrielle, before turning into Surge, was learning the details and the powers of the green Chaos Emerald (Mazuri's emerald), but she never interacted with it because at the time she was just a simple L.Gaia nun and not the Guardian.
LTMEA Surge can just absorb ONE emerald power at the time (pretty much like she does with the chaos drives in the IDW comics) because she can't connect with the gems spiritually, like Sonic and others can do. Surge is too corrupted to open her heart to the emeralds. TBF I never tackle "Super Surge" in LTMEA AU, but I will speak by doing hypothesis: if Surge managed to grab all the 7 emeralds and tried to absorb their energy, then she would end up like Dark Sonic in "Sonic X", because she would collect the negative energy instead of the positive one.