The foliage of your Gerbera looks good, so you are giving it enough water. Does it get too much sun? The blooms on my Gerberas get bleached out unless I give them only morning sun, but I'm in zone 9 and I don't know where you're growing these. You should cut the flower stems all the way to the base as soon as the blooms start to look faded. Is it possible that it's planted too deep? Gerberas like to be planted high, whether they're in a container or in the ground, so that the crown never comes into contact with the soil.