Generally, you can apply for residency after legally living in Ireland for 5 years. This includes General Employment Permit holders. However, as a nice advantage for techies, Critical Skills Employment Permit holders can apply for residency after just 2 years. Once you’ve been granted residency, you won’t need any further employment permits.You’re conflating two issues now (no one mentioned permanent residency), the point is that after 5 years of residency you can apply for citizenship.
This is why you and @marco are on different pages. No one is differentiating here between residence permission and permanent residency. And you're both using the terms interchangeably for "residency".