Hello,
I set ip static address, gateway and dns with nmtui, but I don't ping gateway

Can we resolve it please?

P.S. I not edit /etc/sysconfig/network
it's correct or I must edit this file?

Since you don't tell us what you actually DID, we can't tell you how to correct any possible problems. What kind of interface? New installation or older? There are tutorials on using nmtui:
https://access.redhat.com/documentat...ig_using_nmtui
https://cloudvedas.com/how-to-use-nm...-redhat-linux/

...did you follow any of them?

What kind of interface?
[root@localhost ~]# ip a
2: eno16780032: <BROADCAST,MULTICAST,UO,LOWER_IP> etc etc ...

New installation or older?
Oracle Linux Server 7.1
Kernel 3.10.0-229.el7.x86_64 on an x86_64

This tells us nothing; is this a WIRED interface? Wifi? Did you actually read the list of devices that are supported by nmtui, in the link you were given??? Also, did you follow the nmcli instructions on how to bring the interface UP??? Giving us one line with no details about the interface doesn't let us begin to help.
This tells us nothing. AGAIN: is this a NEW installation or was this server already up/online and you're changing things??? If you cannot/will not provide details, there is nothing we can do to even try to help you. Your best bet would be to contact Oracle support.