The amount of zeaxanthin determined to be in goji berries varies from one study to another.
A 2017 study published in Italian Journal of Food Science found 3,448 mcg of zeaxanthin per single gram of goji berries , as follows:
Zeaxanthin in dried goji berries 
1860 mcg/g of saponified zeaxanthin (186.0 mg/100 g)
1588 mcg/g of unsaponified zeaxanthin (158.8 mg/100 g)
Total: 3448 mcg zeaxanthin per single gram
The same study also found other carotenoids in dried goji berries 
57.0 mcg/g of lutein in dried goji berries (5.7 mg/100 g)
61.0 mcg/g of beta-cryptoxanthin (6.1 mg/100 g)
10.0 mcg/g of beta-carotene (1.0 mg/100 g)
Thus, goji berries are a superior source of zeaxanthin and a minor source of a few other carotenoids.
A 2011 study published in Food Research International found 1,143.7 mcg of zeaxanthin dipalmitate per single gram of goji berries, plus 11.3 – 62.8 mcg/g of zeaxanthin monopalmitate and its two isomers, for a total of 1,155 mcg/g of goji berries. 
A 2014 study published in Journal of Agricultural and Food Chemistry found that “the amounts of zeaxanthin dipalmitate vary from 28 to 54 mg/10 g” in goji berries. That translates to 2,800 to 5,400 mcg of zeaxanthin per single gram of berries. 
Few persons realize that goji berries are also available in a black variety. However, black Goji berries have very low carotenoid content.  They are good sources of antioxidants, but contain few carotenoids.
— Ronald L. Conte Jr.
 Niro, Serena, et al. “Nutritional evaluation of fresh and dried goji berries cultivated in Italy.” Italian Journal of Food Science 29.3 (2017), Table 4;
 Amagase, Harunobu, and Norman R. Farnsworth. “A review of botanical characteristics, phytochemistry, clinical relevance in efficacy and safety of Lycium barbarum fruit (Goji).” Food Research International 44.7 (2011): 1702-1717.
 Karioti, Anastasia, et al. “Validated method for the analysis of goji berry, a rich source of zeaxanthin dipalmitate.” Journal of Agricultural and Food Chemistry 62.52 (2014): 12529-12535.
 Islam, Tahidul, et al. “Comparative studies on phenolic profiles, antioxidant capacities and carotenoid contents of red goji berry (Lycium barbarum) and black goji berry (Lycium ruthenicum).” Chemistry Central Journal 11.1 (2017): 59.