Servals are solitary creatures that are highly territorial. Usually that means they make poor targets for human hunting companions (they much prefer to hunt on their own). Contrast this with dogs, who were most likely bred from wolves, who are pack animals. Check out this video for explanations on traits that make animals more domesticable.
Servals have a short lifespan (compared to humans), reach maturity fairly quickly, and are fairly intelligent (all traits that are helpful with domestication). There is no reason why they wouldn't be useful in vermin patrol, setting up shop near fields and grain stores to protect them from being eaten by rodents. That's how modern cats were domesticated.
This means that servals are probably able to be domesticated but would not do well as a hunting companion.