Weights are variable, but 50 grams is nearly a half cup of ground root for me, so 8 levels tbls or maybe 4-5 heaping ones. If traditional prep techniques aren't solid might be able to use less than 50 grams.
@Adam44 Are you using the Kava King instant as the benchmark for 50 grams? It wouldn't really be comparable to a similar amount of medium grind, because it contains a good bit of fillers in addition to micronized kava, and different varieties and forms of kava will have spectrums of effects that don't readily translate with one another when considering the amounts needed.