gain in something—acquire more of a particular quality:
- The Leader of the Opposition gained significantly in stature as a result of his speech.
gain on something—
1. get closer to a vehicle pursued:
- The police-launch was quickly gaining on the boat.
2. move further ahead of a vehicle:
- The leading group of three continued to gain on the rest of the boats.
3. (of the sea) encroach upon the coast:
- The sea was gradually gaining on the buildings, which at length almost entirely disappeared.