Yes but the fact that it releases slowly means that the material can get "lost" or "stuck" in other material in your stomach and not be absorbed through your stomach lining.
I'm not making on argument on gel caps working or not. I'm simply making an observation that based on personal experience and videos such as what I linked, gel caps can be unreliable to the point of the drug never being absorbed. Three times myself I've had that happen. Back in high school when I was giving stuff to friends two friends took 2C-E capped and never felt anything. As well as the first time I tripped, I was with my best friend, we went out into the countryside, each took 25mg of 4-AcO-DMT capped, and then sat by a river for 4-5 hours. We didn't talk whatsoever so I didn't find out until I felt it was time to go that he'd never felt more than the weed that we smoked at the very beginning. I'd tripped and he hadn't at all. Thirty minutes later we've just left Sonic where he's gotten a milkshake and within 15 minutes of us still driving around roadie'ing he begins to trip.
You can argue all you want but it is empirically unreliable.