The real answer is that yes, Haskell is suited for long-running processes. As with other languages it is up to the developer to find and fix any bugs, including memory leaks.
To do that, and if your program doesn't depend on lazyness, then since GHC 8.0.1 (2016) supports StrictData and Strict language extensions which can tease out space-leaks. (Lazy vs strict is a contentious topic though, so for consult others before you put it in the cabal file :))
cardano-node is an example of a long running large memory footprint program.
As part of work I've two web apps which run months at a time, and are only restarted due to unrelated reasons, e.g updating Let's Encrypt or updates to the operating system. (Both built on top of Warp, so credit probably belongs there)