Does water leaking in always equal water leaking out?

We have had a major leak in our new-ish spa (8 gallons/hour based on our auto-fill meter). When the auto fill is not on, the spa will leak about all the way down. The original PB was fired long ago and other contractors have been in to fix different aspects of what wasn't done. We had a pool company come in to test for leaks but they said the plumbing was all good and nothing pulled dye when testing it. My husband drained the spa and took off the main drain cover. There was ground water gushing in all around the drain component where it meets the plaster, and from a crack in the drain. There was also water gushing in through the screw holes for the drain cover. He is going to attempt to silicon around all this if the water will stop gushing in. We have had quite a bit of rain lately, however. I'd call a pool professional but we have obviously had no luck with anyone doing anything right. It seems like it should be obvious that this is the source of the leak - assuming water is getting in, wouldn't it be true that when the spa is full it is leaking water though these same spots?