If I have a capital gain from the sale of an investment property, does that get added to my personal income in a manner that would effect Roth IRA contribution limits?

Capital gains are included as part of your Adjusted Gross Income (AGI) and as part of your Modified Adjusted Gross Income (MAGI) when determining income limits for contributions to a Roth IRA.
See this IRS website Roth IRA limits - <a rel="nofollow" target="_blank" href="https://www.irs.gov/retirement-plans/amount-of-roth-ira-contributions-that-you-can-make-for-2017">https://www.irs.gov/retirement-plans/amount-of-roth-ira-contributions-that-you-can-make-for-2017</a>

Yes. Capital gains are part of the MAGI calculation that limits your Roth IRA contribution.