Hello! I have the authority (phs000424.v7.p2) to download GTEx V7 raw data. However, I couldn't download any data deposited in "gs s3 ". And these data were released in 2018. I have tried dowload toolkit "prefetch" and sam-dump. "prefetch" have nothing to do while sam-dump report errors "error: item not found while reading file - input object(s) not found". I'm sure I have configured the dbGaP repository key and can download GTEx data deposited in sra. Thank you!
If you are looking for the GTEx raw sequencing data (CRAM files), the most recent GTEx submissions were recently moved to the cloud, on AWS US N. Virginia East (US-amazon-east 1), according to emails I've had with the SRA toolkit devs at NCBI. They make you use fusera and sracp tools to copy the data. Let me know if you need the documentation and instructions, since I just figured it out.
If it's the phenotype data or processed sequencing data (i.e. normalized RNASeq tables), that is still available through the sratoolkit outside of the cloud. SRA staff are pretty responsive for troubleshooting the toolkit: firstname.lastname@example.org.
EDIT 9/27/19: I have gotten many emails asking for detailed steps, so I wrote a post here explaining all that I know. https://cemalley.com/2019/09/27/accessing-gtex-v7-v8-raw-rna-seq-data-in-the-cloud/