Is an i7 5500U Duel Core good for games like Minecraft or GTA?

Definitely… For minecraft its OVERKILL… For GTA… Depending on which GTA you're talking about… If its GTA 5 then you can run it on medium probably… Depending on your graphics card as well

Yes. But you need good Graphic card.

With an i7, you can run most things. You'll most likely be able to run any minecraft modpack, or shaders at about 60fps if you have a good ram and graphics card. As for GTA, you should be good with a good graphics card and some ram too.