If I'm understanding the question, you're asking if there are somatic mutation calls for the same TCGA patients/subjects that have RNAseq available. This data exists for many of the patients, you just have to make sure you use the same TCGA patient barcode to connect the two pieces - the format looks like TCGA-xx-xxxx (e.g. TCGA-21-1070). If you decide to work with the raw somatic mutation files from TCGA, this post Working with MAF files (Mutation Annotation Format) from the TCGA (The Cancer Genome Atlas) is chock full of useful information.

We (at SolveBio) have actually spent a fair amount of time parsing the TCGA somatic mutation files already; it might be a lot easier to use depending on what you're trying to accomplish. First, you have to sign up for SolveBio (it's free for academics). You can browse what the TCGA somatic mutation and patient information data looks like in our Data Library, and you can actually filter out the relevant data in a patient_barcode specific way. For example, you can find all the somatic mutations for one patient by going to the Query Builder, clicking Add Filter, then add patient_barcode as a filter and set it equal to TCGA-21-1070.

We have Python and Ruby clients available so you can actually start working with the somatic mutation data in a programmatic way. I'd be happy to send more detailed instructions for what you're trying to do, if you're interested.