Yeah, Łukasz is the same name as Lucas and because ASCII and internet it's very common to just write it as Lukasz because no matter if you're talking to the native or not, they will know what you mean (it is very common for polish people to omit polish letter altogether when texting/writing informally online because the correct letters can be inferred from the context so why bother pressing that alt key). If you were to pronounce it correctly though it would be something like 'Wookash' (which looks ridiculous in written form but hey)