In the long run, yes.
In the short term, skills increase your chances of winning but do not guarantee it.
There are many types of poker and they all require similar skills, but there are major differences in how different games work. For example, in Omaha, you get 4 closed cards, versus 2 in Texas Hold'em, so your range of potential winning hands is much higher, just like the others. Even in Hold'em, the limit plays much less than the limit, and the strategies between them differ radically.
The basic skills of poker begin with knowing which hands are worth playing and become more complicated when you start looking at your chances of getting the best hand. players, and also how to generate the most shares when you have the best hand - if you scare others by folding them against your unbeatable hand, you will not earn as much money.
I played online for extra money a long time ago. Online poker is very different from what it was at the time - players have progressed tremendously since the "old" days. It takes a lot more skill to win online than in the past. The low limit live games are probably still pretty easy.