if i have lvl 35 fant and use 20 ias gloves

will a 30/398 griefz be enough to reach the maximum frames (6 frame)?

assuming the 'z' in griefz stands for berserker axe as a base: yes
breakpoints for smite with lvl 35 fana are
0 - 8 frames
15 - 7 frames
50 - 6 frames

ty

btw where did you get this info?

source:
https://d2.lc/IAS/

just insert all information and click 'Show IAS table'. Keep in mind that the IAS table does NOT consider the weapon/gear IAS you entered, so the values shown refer to total IAS (not additional IAS)