Helal_1 :
is i7 6700 enoygh for gaming for sever years(6-7 years) without update it
Probably. Assuming you take good care of it, hook it up with a good cooler (Hyper 212 EVO at the very least), run it at safe voltages and frequencies, replace the thermal compound every year or so, keep the heatsink dust-free, don't subject it to a ton of mechanical stress, and keep the motherboard in good shape, it's not unreasonable to expect the chip to last you over 5 years. Games will most likely start to outpace the CPU by the end of that run, though.
I'd suggest getting something like a 6600 or even a 6500 to save some money if you're going to be gaming. That'll give you financial room to upgrade in the nearer future. The 6600 performs almost identically to the 6700 in gaming for $90-$100 less, and the 6500 isn't too far behind for an additional $15-$20 of savings.