How much garbage goes into the Pacific Ocean every year?
I've been looking for information on non-plastic garbage, and haven't had much luck. Plastic waste is an extensively researched topic. I don't have access to  Jambeck et al., Science 2015, but I did find a graphic and summary. The numbers are all year-long totals for 2010.



The study's estimated range of plastic entering the ocean is 4.8 million to 12.7 million metric tons (MMT). 

For the United States we can find some other figures to try to complete the picture. According to the EPA, in 2012, the US generated 251 MMT of municipal solid waste (MSW). Of that, 11.7% was burned, 34.5% was recovered by some sort of recycling, and 53.8% was discarded (Fig. 4). Plastics compose 12.7% of pre-recycling waste but 17.6% of post-recycling waste. Biodegradables (here I'm using food, paper, yard trimmings, and wood, but not textiles) consist of 61.7% of trash before recycling and 52.8% after.

So if we assume those ratios can be applied to the plastics sent to the ocean (8 MMT) you get the following:


Assuming global ocean waste has a similar composition as US
non-recycled waste, there are 63 MMT garbage entering the sea, of
which 39 MMT are biodegradable. 
Assuming global ocean waste has a similar composition as US recycled
waste, there are 45 MMT garbage entering the sea of which 24 MMT are
biodegradable.