Current D-backs have fared pretty well against Chad Gaudin in the past, full statistics here.
I'd expect to see Jason Kubel in the lineup tonight. He is 9 for 13 against Gaudin, including 2 home runs. He also picked up 2 of the 5 hits the D-backs managed against Gaudin the last time they faced him. Aaron Hill, who leads the D-backs with 20 plate appearances against Gaudin, is 7 for 19 with a home run. In only 5 plate appearances, the best Goldschmidt has managed is a walk. Hopefully that will improve.
Despite his struggles, Ian Kennedy has pitched fairly well against the Giants this year. In two starts, he has gone 13 innings, giving up 5 runs on 11 hits. He did walk 5, hit 1, and strike out only 6. His start in San Francisco was one of his better outings of the year, giving up 1 run in 6 innings (one of only two starts all year where he only gave up one run). Both starts were no-decisions, with the D-backs winning in 10 after a David Hernandez blown save in San Francisco, then losing five days later at Chase after Brad Ziegler gave up 2 runs in relief of Kennedy. Historically, Giants other than Buster Posey and Marco Scutaro haven't gone well against Kennedy, who has typically pitched very well against the Giants and has gone 6-2 with an ERA of 2.52 and a WHIP of just over 1.
Hopefully, Kennedy will find his rhythm against a team he typically pitches very well against, and the offense can tee off on Gaudin this time around, after a very disappoint performance earlier this year.