Let me just say there is heavy speculation based on an easter egg that Elsie Hugh's story line may not be finished and therefor her nature may still yet be furthered revealed to the audience.
Here are two links one about another character in relation to Elise and the other about the easter egg specifically:
Vanityfair - S2 Spoilers about Stubbs + tidbit about Elsie:
Easter Egg - Code - Analysis:
Even her statis on the Westworld Wiki is listed as "unknown":
It may also be worth noting that when hosts need repairing, they sometimes need re-sculpting and/or rebuilt and that opens the door on the possibility that in theory, there could be more than one of any given host/android.
UPDATE: Confirmation on Statis of Returning Characters.
Warning Season 2 Spoilers Ahead!!
Elsie Hughes (Shannon Woodward) and Ashley Stubbs (Luke Hemsworth):
Smart-ass programmer Hughes vanished near the end of season 1, while
wary security chief Stubbs was captured by a tribe of Native American
hosts when he went looking for her. Both are alive, but not exactly
doing so hot. “They’re finally getting to experience Westworld as
guests and not in the managerial halls, but I’m not sure they’re
enjoying their experience,” Joy says dryly.
EW - Spoilers: Returning Characters for Season 2