Garland seems a bit frustrated that no one paid attention to Ava's final smile 😊 when no one is watching, as being the deciding proof that she is conscious. but, i think the reason this didn't have the big "woosa" impact that he might have thought it would, is that all of her interactions during the escape attempt already definitely prove that she is sentient. the idea of wanting to "escape" captivity is proof enough to me that she is sentient. to put it in perspective imagine how freaky it would be if my laptop were trying to "escape" its confines of its casing, or wanting to connect to the internet on its own. so her "escape" attempt to me is more than enough