what is the most important component in PC which will help it to make the computer be better for gaming. I reckon motherboard , graphics, processors are all important but which will have the most effect while gaming? is it the graphic cards?
Also does it matter if we have 2 graphics card or 1, will it run the game better with 2?
We'd really need to know your current setup to tell you what to upgrade. Generally speaking, the video card determines how well games run, but if you have a slow processor it's going to be a bottleneck.
Having two of the same graphics card will in fact run better than having only one, but generally you can find a single graphics card that will run even faster and cost even less.