Not yet, but it will be, because phone supports 64 bit processor, if sony wouldn't had any ideas to update to 5.0 + they wouldn't used 64bit processor.
There is already an unofficial lollipop ROM (5.0.1) floating around for the E4g apparently.... The performance improvements are meant to be considerable.. Regardless, I believe it is only a matter of weeks before we get an official release from Sony..