I looked here https://www.vaneck.com.au/funds/gdx/Holdings/
and found Van Eck holds 48M SAR in the GDX so that's about 6% of SAR in the GDX and that makes up about 0.4% of the GDX fund so they are miles under the 8% limit for one stock in the fund.
Obvious Van Eck holds SAR in the GDXJ and probably in some other funds too in smaller amounts.
But I think you would find that they would always keep under the 20% of a stock at which a takeover needs to be launched. They can't own companies outright. They need the flexibility of being able to increase or reduce holdings to follow their fund's rules.
