Is it enough to choose a capacitor that can withstand the final
voltage?
It absolutely is but, I think where you might be getting confused is the definition of the "final voltage". It's not the 8 kV initial voltage that the ESD generator can produce into an open circuit; it's the voltage that appears across the capacitor (much much less than 8 kV) due to the internal series resistance of the ESD generator/gun. That internal resistance (and the ESD capacitor in question) form a low-pass RC network that significantly limits the build-up of voltage across that ESD capacitor.
In the picture below, the 150 pF capacitor is charged up to (say) 8 kV. These are internal ESD gun components and will be subject to the full kV rating but, that's not your problem. The important component (still internal to the ESD gun) is the 330 Ω resistor. It will limit the peak voltage that can be produced across your ESD protection capacitor. And, of course, you have to choose a value of ESD capacitor that limits the voltage sufficiently to protect your vulnerable circuit AND is limited below the maximum voltage rating of the ESD capacitor.

(Image source: Keith Armstrong - Design Techniques for EMC – Part 6)
Where can I find this information for a given package size,
capacitance and voltage rating?
You won't find it because you have to calculate it. Manufacturers don't know what your victim circuit might be able to safely withstand and therefore they cannot tell you what value capacitor to choose. Given also that there are a few different ESD requirements specifications, this makes definitive recommendations improbable.
But, if you have a simulator (highly recommended these days for any level of designer) it's easy to set the initial conditions on the 150 pF capacitor to be 8 kV and see what the voltage rises to on your prospective ESD capacitor based on capacitance value.
Regarding the capacitors proposed in the question, the data sheet is a little ambiguous over the part numbers but, nevertheless, I think they tie in with this range on the Kemet website. They are described by Kemet as being "SMD ESD Rated Commercial Grade" and, if I focus on a 10 nF 0603 part, it has an ESR curve like this: -

Basically the ESR is 100 mΩ and this ought to be considered when making calculations or, just make a simulation using that ESR value. You can also check the ESL: -

It's pretty good; it doesn't rise about 500 pH (pico henries) but, you should still use it in your simulation just to ensure there are no extravagant ringing artefacts that might cause voltage overshoot problems.
You should also check out what Kemet say about the peak voltages and currents. This just doesn't only apply to ESD but normal operation as well: -

Factor all these things in and you should be good to go. Anyway, here's a quick simulation of a 10 nF capacitor being discharged into. I've taken the liberty of speeding up the charge process into the 150 pF capacitor just to make things easier to see: -

And here are the waveforms: -

Under these circumstances, the ESD capacitor rises towards 195\$\color{red}{\boxed{^1}}\$ volts for a closed switch duration of 10 μs (that begins at 0.5 ms). I'm sure, if you had a simulator you could reproduce this and add in ESR and ESL to the ideal capacitor model used.
\$\color{red}{\boxed{^1}}\$ 195 volts is a little high due to the liberty I took when reducing the 50 MΩ resistor to 100 kΩ. I took this liberty to speed up the 150 pF charge time so that the sim result was more easily viewable. In reality, with basic charge redistribution from the 150 pF capacitor to the 10 nF capacitor, the peak voltage would be: -
$$\text{150 pF}\times\text{ 8,000 volts} = \text{(10 nF + 150 pF)}\times\text{ final voltage}$$